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   2704篇
  免费   149篇
  国内免费   9篇
耳鼻咽喉   21篇
儿科学   235篇
妇产科学   53篇
基础医学   271篇
口腔科学   64篇
临床医学   185篇
内科学   530篇
皮肤病学   119篇
神经病学   117篇
特种医学   84篇
外科学   382篇
综合类   62篇
预防医学   136篇
眼科学   185篇
药学   262篇
中国医学   11篇
肿瘤学   145篇
  2023年   24篇
  2022年   58篇
  2021年   97篇
  2020年   55篇
  2019年   65篇
  2018年   81篇
  2017年   86篇
  2016年   95篇
  2015年   83篇
  2014年   132篇
  2013年   159篇
  2012年   196篇
  2011年   186篇
  2010年   108篇
  2009年   90篇
  2008年   149篇
  2007年   127篇
  2006年   122篇
  2005年   104篇
  2004年   92篇
  2003年   63篇
  2002年   51篇
  2001年   47篇
  2000年   48篇
  1999年   38篇
  1998年   21篇
  1997年   23篇
  1996年   10篇
  1995年   17篇
  1993年   16篇
  1992年   41篇
  1991年   24篇
  1990年   34篇
  1989年   33篇
  1988年   34篇
  1987年   26篇
  1986年   20篇
  1985年   28篇
  1984年   21篇
  1983年   10篇
  1980年   8篇
  1979年   21篇
  1978年   13篇
  1977年   7篇
  1975年   8篇
  1974年   13篇
  1973年   14篇
  1972年   8篇
  1971年   8篇
  1965年   7篇
排序方式: 共有2862条查询结果,搜索用时 15 毫秒
101.
An elderly male with Bipolar Affective Disorder (BPAD) developed reversible ototoxicity, manifesting as bilateral sensory-neural hearing loss (SNHL) with administration of olanzapine.KEY WORDS: Olanzapine, bipolar affective disorder, ototoxicity  相似文献   
102.
103.
A 4 A electron-density map of Pf1 filamentous bacterial virus has been calculated from x-ray fiber diffraction data by using the maximum-entropy method. This method produces a map that is free of features due to noise in the data and enables incomplete isomorphous-derivative phase information to be supplemented by information about the nature of the solution. The map shows gently curved (banana-shaped) rods of density about 70 A long, oriented roughly parallel to the virion axis but slewing by about 1/6th turn while running from a radius of 28 A to one of 13 A. Within these rods, there is a helical periodicity with a pitch of 5 to 6 A. We interpret these rods to be the helical subunits of the virion. The position of strongly diffracted intensity on the x-ray fiber pattern shows that the basic helix of the virion is right handed and that neighboring nearly parallel protein helices cross one another in an unusual negative sense.  相似文献   
104.

Background

Evaluation of medical students during the surgical clerkship is controversial. Performance is often based on subjective scoring, whereas objective knowledge is based on written examinations. Whether these measures correspond or are relevant to assess student performance is unknown. We hypothesized that student evaluations correlate with performance on the National Board Of Medical Examiners (NBME) examination.

Methods

Data were collected from the 2011–2012 academic year. Medical students underwent a ward evaluation using a seven-point Likert scale assessing six educational competencies. Students also undertook the NBME examination, where performance was recorded as a percentile score adjusted to national standards.

Results

A total of 129 medical students were studied. Scores on the NBME ranged from the 52nd to the 96th percentile with an average in the 75th percentile (±9). Clerkship scores ranged from 3.2–7.0 with a mean of 5.7 (±0.8). There was a strong positive association between higher NBME scores and higher clerkship evaluations shown by a Pearson correlation coefficient of 0.47 (P < 0.001). Students clustered with below average ward evaluations (3.0–4.0) were in the 69.5th percentile of NBME scores, whereas students clustered with above average ward evaluations (6.0–7.0) were in the 79.2th percentile (P < 0.001).

Conclusions

A strong positive relationship exists between subjective ward evaluations and NBME performance. These data may afford some confidence to surgical faculty and surgical resident ability to accurately evaluate medical students during clinical clerkships. Understanding factors in student performance may help in improving the surgical clerkship experience.  相似文献   
105.

Background

Despite extensive translational research, no validated biomarkers predictive of bevacizumab treatment outcome have been identified.

Methods

We performed a meta-analysis of individual patient data from six randomized phase III trials in colorectal, pancreatic, lung, renal, breast, and gastric cancer to explore the potential relationships between 195 common genetic variants in the vascular endothelial growth factor (VEGF) pathway and bevacizumab treatment outcome.

Results

The analysis included 1,402 patients (716 bevacizumab-treated and 686 placebo-treated). Twenty variants were associated (P < 0.05) with progression-free survival (PFS) in bevacizumab-treated patients. Of these, 4 variants in EPAS1 survived correction for multiple testing (q < 0.05). Genotype-by-treatment interaction tests revealed that, across these 20 variants, 3 variants in VEGF-C (rs12510099), EPAS1 (rs4953344), and IL8RA (rs2234671) were potentially predictive (P < 0.05), but not resistant to multiple testing (q > 0.05). A weak genotype-by-treatment interaction effect was also observed for rs699946 in VEGF-A, whereas Bayesian genewise analysis revealed that genetic variability in VHL was associated with PFS in the bevacizumab arm (q < 0.05). Variants in VEGF-A, EPAS1, and VHL were located in expression quantitative loci derived from lymphoblastoid cell lines, indicating that they affect the expression levels of their respective gene.

Conclusions

This large genetic analysis suggests that variants in VEGF-A, EPAS1, IL8RA, VHL, and VEGF-C have potential value in predicting bevacizumab treatment outcome across tumor types. Although these associations did not survive correction for multiple testing in a genotype-by-interaction analysis, they are among the strongest predictive effects reported to date for genetic variants and bevacizumab efficacy.  相似文献   
106.
107.

Objective

Recent hypertension guidelines recommend initiation of treatment with a fixed dose combination of two drugs for more effective and quicker blood pressure control. Few of these have been assessed for efficacy and acceptability. This study examines the short term blood pressure control and acceptability of perindopril, with or without its fixed dose combinations (FDC) with amlodipine and Indapamide in younger patients.

Methods

In a multicentre prospective observational study, patients with stage 1 hypertension were prescribed perindopril 4 mg per day. Those with stage 2 or 3 hypertension were prescribed a single tablet per day of 4 mg perindopril and 5 mg amlodipine (COVERSYL AM), or 4 mg perindopril and 1.25 mg indapamide (COVERSYL PLUS)for 45 days. The primary outcomes were the frequency of patients achieving blood pressure control and the adverse effect of pedal edema.

Results

Of 426 patients, with a mean age of 45 years, distributed throughout India, and an average (SD) baseline systolic/diastolic blood pressure of 157.2 (13.5)/98.6 (7.4), 303 (71.1%) achieved blood pressure control. Mean (SD) SBP/DBP decreased from baseline by 26.9 (12.6), and DBP by 15.4 (7.2) mm Hg. Few patients discontinued treatment, and the frequency of cough that interfered with sleep and ankle edema was low.

Conclusion

In patients requiring combination antihypertensive treatment, the regimen of perindopril alone or its FDC with Indapamide or amlodipine reduces blood pressure effectively, resulting in high rates of blood pressure control over the short term, with a low frequency of side effects including cough and pedal edema.  相似文献   
108.
The purpose of this study was to investigate the phase behavior of cyclophosphamide (CPA) during various stages of lyophilization, with special emphasis on obtaining crystalline CPA monohydrate (CPA-MH) in the lyophilized product. Subambient differential scanning calorimetry and low-temperature X-ray diffractometry (LTXRD) were used to study the phase behavior of CPA solution (3.7% w/v). In situ lyophilization in LTXRD chamber was used to monitor the phase transitions occurring during the drying stages. Finally, the implications of these findings were confirmed by freeze-drying the aqueous solution in a laboratory-scale freeze-dryer. The results suggested that CPA remains amorphous during freeze concentration, with a Tg' of ?50°C. However, its crystallization as CPA-MH can be induced by annealing the frozen solution between ?5°C and ?10°C. In situ lyophilization in LTXRD showed that the CPA-MH crystallized during annealing, rapidly dehydrated during primary drying, thereby causing structural collapse. The dehydration of CPA-MH can be prevented by lowering the escaping tendency of water molecules from the crystal lattice of CPA-MH by maintaining the chamber pressure to 300, 400, or 500 mTorr. This study highlights the relationship of process parameters used during lyophilization with the solid form of lyophilized CPA.  相似文献   
109.
Isolated IgG4 tubulointerstitial nephritis (TIN) is a rare disorder characterized by raised serum IgG4 levels and histological findings of dense lymphoplasmacytic infiltrates rich in IgG4 positive plasma cells. We report a case of isolated IgG4 TIN that presented with acute kidney injury in an 84 year old man with a polyclonal increase in his total IgG and a raised IgE of 381 kUA/L but without evidence of systemic autoimmunity. We draw a parallel with IgG4-related autoimmune pancreatitis and show raised levels of circulating regulatory T cells. Importantly the plasma levels of the T regulatory cell cytokine, IL10, the TH1 cytokines IL12 and IFNγ, the proinflammatory TNF α and immune regulatory IL27 were all highly raised. Furthermore, the level of IL21 that promotes IgG4 production was also very significantly elevated. These results suggest efforts of the immune system to reduce inflammation and suppress an exaggerated Th2 response. A raised serum IgG in the setting of acute kidney injury and in the absence of autoimmunity and chronic infection should encourage an assessment of the IgG subclasses. Prompt steroid treatment of those with a raised IgG4 may reduce ongoing renal damage.  相似文献   
110.
We report a case of aggressive pilomatrixoma (PMX) in a 25‐year‐old male who presented with swelling in left supraclavicular region of 2‐month duration. A diagnosis of small round cell tumor was suggested on fine‐needle aspiration cytology. He underwent wide excision of the mass. On histomorphological examination, a diagnosis of aggressive PMX was made. The swelling recurred after 3 months of complete resection and on examination had similar morphological features. The case is presented because of the potential diagnostic difficulties on cytological examination and rare occurrence of aggressive variant of PMX. Diagn. Cytopathol. 2014;42:906–911. © 2014 Wiley Periodicals, Inc.  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