首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1005篇
  免费   51篇
  国内免费   1篇
耳鼻咽喉   5篇
儿科学   53篇
妇产科学   22篇
基础医学   95篇
口腔科学   22篇
临床医学   92篇
内科学   153篇
皮肤病学   8篇
神经病学   124篇
特种医学   42篇
外科学   218篇
综合类   2篇
一般理论   1篇
预防医学   66篇
眼科学   16篇
药学   83篇
中国医学   1篇
肿瘤学   54篇
  2023年   4篇
  2022年   9篇
  2021年   26篇
  2020年   15篇
  2019年   39篇
  2018年   64篇
  2017年   42篇
  2016年   43篇
  2015年   27篇
  2014年   51篇
  2013年   53篇
  2012年   51篇
  2011年   50篇
  2010年   48篇
  2009年   23篇
  2008年   38篇
  2007年   35篇
  2006年   41篇
  2005年   28篇
  2004年   35篇
  2003年   25篇
  2002年   23篇
  2001年   16篇
  2000年   23篇
  1999年   20篇
  1998年   6篇
  1997年   8篇
  1996年   6篇
  1995年   6篇
  1993年   6篇
  1992年   17篇
  1991年   9篇
  1990年   14篇
  1988年   16篇
  1987年   20篇
  1986年   14篇
  1985年   10篇
  1984年   12篇
  1983年   6篇
  1982年   5篇
  1981年   4篇
  1979年   5篇
  1978年   8篇
  1977年   6篇
  1974年   3篇
  1973年   4篇
  1972年   11篇
  1970年   3篇
  1968年   3篇
  1967年   5篇
排序方式: 共有1057条查询结果,搜索用时 15 毫秒
21.
Background: Deficits in the production of complex structures have been widely documented in non-fluent forms of aphasia. Nevertheless, the data available on fluent deficits are scarcer. In both cases, reduced complexity is attributed to syntactic factors. In the related field of syntactic theory, there exist a number of studies on the production of non-brain damaged (NBD) subjects which try to account for the existence of two alternative constructions in embedded complement clauses in English (as in I think that the situation will improve/I think the situation will improve). The absence of that in the embedded clauses of verbs like say, know or think in colloquial English is very frequent and this suggests that verbs of this type may select a clause lacking a complementiser phrase (CP) layer, namely tense phrase (TP). The presence of that is taken to be the result of insertion, which is triggered by cues associated to contextual factors like register.

Aims: To compare the presence and absence of the complementiser that in the speech of English subjects diagnosed with aphasia with the same phenomenon in NBD subjects with the objective of clarifying the nature of the phenomenon of that-omission.

Methods &; Procedures: We carried out an analysis of spontaneous speech that included the performance of 200 individuals brought together by the AphasiaBank project. Two groups were included in the study, an experimental group comprising 100 individuals diagnosed as aphasic according to the standards of the Western Aphasia Battery (WAB), and a control group including 100 non-brain damaged control subjects ( NBDs).

Outcomes &; Results: This study shows that the asymmetries across populations (NBDs vs. subjects with aphasia) are restricted to the number of occurrences of subordinate clauses. NBD subjects produce more embeddings than subjects diagnosed with fluent aphasia (although they do produce embedded clauses and crucially prefer the “omission” option) and subjects with non-fluent aphasia.

Conclusions: Our results confirm the findings on fluent aphasias as for the presence of deficits with complex constructions. These results may be regarded as evidence for the claim that TP is the default selection for the verbs analysed.  相似文献   
22.
Background: In the cognitive neurolinguistic approach to lexical deficits in aphasia, impaired levels of processing are localised in a cognitive model. Model-oriented treatment may target these impaired components. Thus a precise assessment of the disorder is crucial. Connectionist models add to this by using computer simulation to specify the details of the functioning of these components. The connectionist semantic-phonological model of lexical access (Dell, Martin, & Schwartz, 2007 Dell, G. S., Martin, N. and Schwartz, M. F. 2007. A case-series test of the interactive two-step model of lexical access: Predicting word repetition from picture naming. Journal of Memory and Language, 56: 490520. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]; Schwartz, Dell, Martin, Gahl, & Sobel, 2006 Schwartz, M. F., Dell, G. S., Martin, N., Gahl, S. and Sobel, P. 2006. A case-series test of the interactive two-step model of lexical access: Evidence from picture naming. Journal of Memory and Language, 54: 223264.  [Google Scholar]) explores the impairment by simulating error patterns in naming and repetition.

Aims: The purpose of the present study was to investigate the model's range of application as a diagnostic tool, and to derive recommendations for the model's use in clinical settings.

Methods & Procedures: We demonstrate how we adapted the error analysis to 15 German-speaking patients with aphasia, analysed the model's accuracy in assessing naming and repetition disorders, and explained deviations between the error pattern produced by each patient and the one produced by the model's simulation by appealing to an extended version of the model.

Outcomes & Results: Overall, the model yielded good fits of the patients' error patterns. Larger model–patient deviations could be explained by the model's limited set of lesionable components.

Conclusions: The “connectionist diagnosis” of naming and repetition disorders in the semantic-phonological model is a reasonable tool in model-oriented assessment. However, the diagnosis needs to be complemented by further language tests.  相似文献   
23.
24.
In this paper, we describe the approach to the characterization of an unusual material seized by the judicial authority, near Brescia City in Northern Italy. Usual analyses such as thin-layer chromatography, gas chromatography (GC)–flame ionization detection, and GC/mass spectrometry (MS) did not show the presence of drugs of abuse, in particular amphetamine-like compounds. The major solid component was identified as cornstarch; then taking into account the strong aromatic scent of the seized material; a preliminary experiment for volatile organic compounds was carried out by headspace (HS)-GC/MS. This analysis tentatively evidenced the presence of 1-phenyl-2-propanone (P2P), an amphetamine precursor. Therefore, we developed and optimized a new analytical method for determination of P2P in seized materials by HS-GC/MS. We also synthesized P2P, with the permission of the Ministry of Health, to have it as reference standard, because of its being illegal and the difficulty in obtaining it. This case had some analogies with the cases referred to as “wet amphetamine” by the judicial authority, in which amphetamines are sold mixed with P2P. The possible use of the material could be the production of tablets made of cornstarch with an aromatic scent similar to that of amphetamines to deceive consumers and to sell them as a drug of abuse.  相似文献   
25.

Introduction

In renal cell carcinoma (RCC), lymph node status at preoperative imaging is affected by a non-negligible false-positive rate. We aimed to investigate which factors are related to a concordance between clinical suspicion and pathological confirmation of lymph node invasion (LNI).

Methods

At a single tertiary care institution, 2954 RCC patients underwent either partial or radical nephrectomy. For the aim of the study, only clinically positive lymph node cases were included (cN1). Statistical analyses assessed the concordance between preoperative and pathological nodal status.

Results

Preoperative axial CT scans revealed 424 (14.4 %) patients showing at least one enlarged lymph node suspected for LNI (cN1). All lymphadenopathies were removed at surgery, and LNI was pathologically confirmed (pN1) in 122 patients (28.8 %). When focusing the analyses on clinical characteristics (variables known before surgery), metastases at diagnosis [OR 3.0 (95 %1.9–4.8), p < 0.001] and tumor size [OR 1.1 (95 % 1.1–1.2), p < 0.001] were the two most informative predictors of concordance between clinical and pathological nodal status. Concordance was also more likely in patients with papillary type II tumors (55.6 %) relative to papillary type I (38.1 %), clear cell (27.7 %) and chromophobe (8.3 %) tumors. At multivariable analyses, none of the considered blood markers resulted to be independently associated with LNI.

Conclusions

Roughly 70 % of patients showing a suspected lymph node preoperatively do not show LNI at the final pathological report. Among patients with clinically positive nodes, clinical tumor size and metastases at diagnosis represent the most informative and independent predictors of confirmed LNI at final pathology.
  相似文献   
26.

Introduction

The aim of the study was to identify the appropriate level of Charlson comorbidity index (CCI) in older patients (>70 years) with high-risk prostate cancer (PCa) to achieve survival benefit following radical prostatectomy (RP).

Methods

We retrospectively analyzed 1008 older patients (>70 years) who underwent RP with pelvic lymph node dissection for high-risk prostate cancer (preoperative prostate-specific antigen >20 ng/mL or clinical stage ≥T2c or Gleason ≥8) from 14 tertiary institutions between 1988 and 2014. The study population was further grouped into CCI < 2 and ≥2 for analysis. Survival rate for each group was estimated with Kaplan–Meier method and competitive risk Fine-Gray regression to estimate the best explanatory multivariable model. Area under the curve (AUC) and Akaike information criterion were used to identify ideal ‘Cut off’ for CCI.

Results

The clinical and cancer characteristics were similar between the two groups. Comparison of the survival analysis using the Kaplan–Meier curve between two groups for non-cancer death and survival estimations for 5 and 10 years shows significant worst outcomes for patients with CCI ≥ 2. In multivariate model to decide the appropriate CCI cut-off point, we found CCI 2 has better AUC and p value in log rank test.

Conclusion

Older patients with fewer comorbidities harboring high-risk PCa appears to benefit from RP. Sicker patients are more likely to die due to non-prostate cancer-related causes and are less likely to benefit from RP.
  相似文献   
27.

Purpose

Local tumor ablation (LTA) and partial nephrectomy (PN) represent treatment alternatives for patients diagnosed with small renal mass and both may result in renal function detriments. The aim of the study was to compare renal function detriments after LTA or PN.

Methods

A Surveillance epidemiology and End Results-Medicare-linked retrospective cohort of 2850 T1 kidney cancer patients who underwent LTA or PN was abstracted. Short-term outcomes consisted of 30-day acute kidney injury (AKI) and 30-day dialysis rates. Long-term outcomes consisted of episodes of AKI, mild and moderate–severe chronic kidney disease (CKD), end-stage renal disease, hemodialysis and anemia in CKD. Analyses consisted of propensity score matching, logistic and Cox regression.

Results

After propensity score matching, 1122 patients remained. The 30-day incidence of AKI was 4.6 % after LTA and 9.4 % after PN. In multivariable analyses (MVAs), LTA was associated with a lower AKI rate (OR 0.42; p = 0.001). The 30-day incidence of any dialysis was <2 % after either LTA or PN. In MVA, LTA was not associated with a lower rate of any dialysis (OR 0.43; p = 0.2). At long-term assessment, both the unadjusted and adjusted rates of all six examined end points were not different between LTA and PN (all p > 0.5).

Conclusions

LTA offers short-term protective effect from AKI. The short-term rates of any dialysis treatment are similar after either LTA or PN. At long-term assessment, LTA and PN renal function detriment rates are not different. Concern for long-term functional outcomes should not be a barrier for PN.
  相似文献   
28.
Dell DD 《Nursing》2007,37(2):61-64
Invisible and incurable, this disorder can wreak havoc with your patient's life. Find out how to get her back on track. Fibromyalgia, a complex, chronic disorder of pain processing, is thought to be the most common cause of generalized musculoskeletal pain in women ages 20 to 55. This disorder, which affects the muscles, ligaments, and tendons, occurs in 3 to 6 million Americans, mostly women. Some patients are affected only mildly, but up to 30% have symptoms that seriously impair their quality of life.  相似文献   
29.
Long-term studies (32-49 wk) of the turnover of plasma cholesterol were conducted in 24 subjects. Eight subjects were normilipidemic, six had hypercholesterolemia, eight had hypercholesterolemia and hypertriglyceridemia, and two had hypertriglyceridemia alone. 10 of the hyperlipidemic patients had a definite familial disorder. In all subjects (except one for whom complete data were not available), the same three-pool model previously described gave the best fit for the data. The parameters of the three-pool model observed in the normal subjects were compared with the model parameters found in the patients with the different kinds of hyperlipidemia. In addition, single and multiple regression analyses were conducted to explore the relationships between the model parameters and various physiological variables, including age, body size, and serum lipid concentrations. Using this approach, significant differences between groups, or correlations with serum lipid levels were seen for several parameters of the three-pool model: the production rate (PR); the size of the rapidly exchanging pool 1 (M1); all estimates of the size of the most slowly equilibrating pool 3 (M3); and the rate constant k21. The PR in normal subjects (1.14 +/- 0.19 g/day, mean +/- SD) was not significantly different from that found in patients with hypercholesterolemia, with or without hypertriglyceridemia. The major determinant of cholesterol PR was overall body size, expressed either as total body weight or as surface area. The correlations between PR and indices of adiposity (percent ideal weight and excess weight), although statistically significant, were much weaker in this nonobese population. After adjustment for body size variation, cholesterol PR was not correlated with the serum cholesterol concentration but was probably (P less than 0.05) correlated with the triglyceride concentration. When the two patients with very high triglyceride concentrations were excluded, however, no correlation was observed between adjusted PR and triglyceride level. It is probable that hypertriglyceridemic patients represent a heterogeneous population, in which the majority do not show increased cholesterol PR. M1 was correlated with all body size variables, but most strongly with excess weight. After adjusting for the effects of body size, M1 was also correlated and triglyceride. Major differences were found in the relationships between the physiological variables and the sizes of pools 2 and 3. M2 was correlated neither with any of the indices of body size or adiposity, nor with the serum levels of either cholesterol or triglyceride. In contrast, all estimates of M3 were correlated with indices of adiposity (but not of overall body size) and with the serum cholesterol concentration. Thus, the amount of cholesterol in slowly equilibrating tissue sites appears to particularly increase with elevations of the serum cholesterol level. The results also confirm previous data that adipose tissue cholesterol is an important part of pool 3.  相似文献   
30.
Antipsychotic-induced weight gain (AIWG) is a prevalent side effect of antipsychotic treatment, particularly with second generation antipsychotics, such as clozapine and olanzapine. At this point, there is virtually nothing that can be done to predict who will be affected by AIWG. However, hope for the future of prediction lies with genetic risk factors. Many genes have been studied for their association with AIWG with a variety of promising findings. This review will focus on genetic findings in the last year and will discuss the first epigenetic and biomarker findings as well. Although there are significant findings in many other genes, the most consistently replicated findings are in the melanocortin 4 receptor (MC4R), the serotonin 2C receptor (HTR2C), the leptin, the neuropeptide Y (NPY) and the cannabinoid receptor 1 (CNR1) genes. The study of genetic risk variants poses great promise in creating predictive tools for side effects such as AIWG.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号