全文获取类型
收费全文 | 5311篇 |
免费 | 272篇 |
国内免费 | 48篇 |
专业分类
耳鼻咽喉 | 25篇 |
儿科学 | 202篇 |
妇产科学 | 162篇 |
基础医学 | 740篇 |
口腔科学 | 127篇 |
临床医学 | 378篇 |
内科学 | 1102篇 |
皮肤病学 | 110篇 |
神经病学 | 410篇 |
特种医学 | 216篇 |
外国民族医学 | 1篇 |
外科学 | 727篇 |
综合类 | 161篇 |
预防医学 | 558篇 |
眼科学 | 44篇 |
药学 | 338篇 |
中国医学 | 32篇 |
肿瘤学 | 298篇 |
出版年
2023年 | 27篇 |
2022年 | 46篇 |
2021年 | 91篇 |
2020年 | 58篇 |
2019年 | 75篇 |
2018年 | 99篇 |
2017年 | 66篇 |
2016年 | 84篇 |
2015年 | 106篇 |
2014年 | 142篇 |
2013年 | 199篇 |
2012年 | 207篇 |
2011年 | 220篇 |
2010年 | 161篇 |
2009年 | 143篇 |
2008年 | 217篇 |
2007年 | 235篇 |
2006年 | 256篇 |
2005年 | 219篇 |
2004年 | 235篇 |
2003年 | 261篇 |
2002年 | 228篇 |
2001年 | 219篇 |
2000年 | 173篇 |
1999年 | 158篇 |
1998年 | 83篇 |
1997年 | 69篇 |
1996年 | 71篇 |
1995年 | 65篇 |
1994年 | 57篇 |
1993年 | 36篇 |
1992年 | 108篇 |
1991年 | 69篇 |
1990年 | 111篇 |
1989年 | 104篇 |
1988年 | 88篇 |
1987年 | 81篇 |
1986年 | 87篇 |
1985年 | 78篇 |
1984年 | 71篇 |
1983年 | 32篇 |
1982年 | 39篇 |
1981年 | 28篇 |
1980年 | 39篇 |
1979年 | 50篇 |
1978年 | 30篇 |
1977年 | 41篇 |
1976年 | 29篇 |
1972年 | 25篇 |
1968年 | 25篇 |
排序方式: 共有5631条查询结果,搜索用时 15 毫秒
81.
82.
目的 研究应用神经反应遥测 (neuralresponsetelemetry ,NRT)技术 ,测试电诱发复合动作电位 (electrically evokedcompoundactionpotential,ECAP)阈值以指导小儿人工耳蜗映射调图的策略与时机。方法 应用NRT3 0软件对幅值增长函数进行线性拟合 ,确定ECAP阈值。比较 6例儿童植入者在术后 1、2、3个月ECAP阈值的变化 ,同时比较 7例儿童术中、术后ECAP阈值的差异。结果ECAP幅值增长函数在接近阈值或进入饱和时不再呈线性。术后ECAP阈值保持稳定。各导电极的术中ECAP阈值比术后阈值平均高约 15CL ,二者有显著性相关 (R2 =0 915 4)。结论 应选取幅值增长函数的直线段部分进行拟合以确定ECAP阈值。术后应用ECAP阈值指导小儿映射调图时 ,测试一次ECAP阈值即可。术中ECAP阈值可用作开机时映射图的C值 相似文献
83.
Cornelius Schüle Flavia di Michele Thomas Baghai Elena Romeo Giorgio Bernardi Peter Zwanzger Frank Padberg Augusto Pasini Rainer Rupprecht 《Neuropsychopharmacology》2003,28(3):577-581
There is evidence from preclinical and clinical studies that concentrations of neuroactive steroids are altered in depression and normalize after antidepressant pharmacotherapy. However, no data are available concerning the impact of sleep deprivation on the concentrations of neuroactive steroids. A total of 29 drug-free patients (12 men, 17 women) suffering from major depression according to DSM-IV criteria were treated with partial sleep deprivation (PSD). Response to PSD was defined as a reduction of at least 30% according to the six-item version of the Hamilton depression scale (6-HAMD). Plasma samples were taken the day before and after PSD (days 0 and 1) and after one night of recovery sleep (day 2) at 8:00 am. The samples were quantified for neuroactive steroids by means of a highly sensitive and specific combined gas chromatography/mass spectrometry analysis. There was no influence of PSD on the concentrations of neuroactive steroids either in PSD responders (n=20) or in nonresponders (n=9). However, nonresponders showed significantly higher concentrations of 3alpha,5alpha-tetrahydroprogesterone (3alpha,5alpha-THP), 3alpha,5beta-tetrahydroprogesterone (3alpha,5beta-THP), and dehydroepiandrosterone (DHEA) before or after PSD compared to responders. In contrast to antidepressant drugs, which correct the dysequilibrium of neuroactive steroids in major depression within several weeks, PSD does not affect the concentrations of neuroactive steroids either in responders or in nonresponders. 相似文献
84.
A Patócs E Karádi M Tóth I Varga N Szücs K Balogh J Majnik E Gláz K Rácz 《European journal of cancer prevention》2004,13(5):403-409
The aims of this study were to estimate the prevalence of phaeochromocytomas among adrenal tumours and to analyse the clinical and biochemical features of sporadic and hereditary tumours. Our series of 609 adrenal tumours evaluated between January 1995 and July 2003 was reviewed. Catecholamine content in phaeochromocytoma tissues was also determined and correlated with clinical behaviour and biochemical parameters of patients. Forty-one (6.7%) of the 609 patients had phaeochromocytomas, of which 28 were sporadic (25 benign and three malignant) and 13 (all benign) were associated with hereditary diseases (multiple endocrine neoplasia type 2A in seven cases from four unrelated families carrying mutations of the RET gene, von Hippel-Lindau disease in two unrelated cases with mutations of the VHL gene, and type 1 neurofibromatosis in four unrelated cases). Bilateral tumours were found in three patients with hereditary syndromes and in one sporadic case. Tumour diameter was slightly but not significantly greater in patients with hereditary than in those with sporadic tumours. Systolic but not diastolic blood pressure was significantly higher in patients with sporadic compared with those with hereditary tumours, but comparison of other clinical data and biochemical parameters indicated an absence of significant differences in the mean age, presenting symptoms, heart rate, or fasting serum glucose levels. Tissue catecholamine content measured in 8 sporadic and 5 hereditary phaeochromocytomas was highly variable and it failed to show significant differences between hereditary and sporadic tumours. These results indicate a high proportion of hereditary diseases among patients with phaeochromocytomas. Genetic and clinical testing for hereditary diseases may be of great help to offer an appropriate treatment, follow-up and family screening for these patients. 相似文献
85.
人α干扰素诱导骨肉瘤细胞Anoikis凋亡 总被引:1,自引:0,他引:1
目的:恶性肿瘤细胞逃避Anoikis凋亡的特性是其原位侵袭和远处转移的一个重要原因。本文旨在研究应用人干扰素(IFN)α2a诱导骨肉瘤细胞出现Anoikis凋亡,并深入探讨其产生机理及信号传导途径。方法:采用抑制接触培养法建立细胞Anoikis凋亡诱导模型。观察IFN-α2a诱导骨肉瘤细胞MG-63产生的Anoikis凋亡。TUNEL法形态学检测MG-细胞凋亡,流式细胞仪定量检测细胞凋亡程度和细胞表面整联蛋白受体表达。特异性底物切开法检测半胱氨酸天门冬氨酸特异性蛋白酶(cysteine aspartate-specific proteases,caspase)信号途径。结果:人IFN-α2a可明显诱导骨肉瘤细胞MG-63产生Anoikis现象,并诱导了MG-63细胞caspase-8和caspase-3的活性,但IFN对整联蛋白亚单位α4,α5及αv无明显影响,上述整联蛋白封闭抗体对IFNα-2a诱导的MG-63细胞Anoikis凋亡无明显影响。结论:人干扰素α2a可以在体外通过调节细胞caspase信号途径,诱导骨肉瘤细胞MG-63产生Anoikis现象,从而抑制骨肉瘤的转移。 相似文献
86.
Gruppo di lavoro per la sorveglianza del mesotelioma in Romagna 《La Medicina del lavoro》2000,91(6):575-586
The aim of this study was to evaluate the prevalence and major correlates of occupational exposure to asbestos among the 125 cases of mesothelioma of the pleura, peritoneum, and pericardium registered in the Romagna Region of Italy between 1986 and 1998. Adequate occupational information was obtained for 122 (98%) cases. Among these, the male:female ratio was 81:41 (2.0), the median age was 68 years (range, 25-92), and the pleural location accounted for 96 (79%) cases. According to job history, 61 (50%) cases had had definite (23), probable (12), and possible (26) occupational exposure to asbestos. The probability (multiple logistic regression estimate) was greater for males (odds ratio, 10.8) but decreased for cases with mesothelioma of the peritoneum and pericardium (0.21) as well as those above the median age (0.38). Time period, residence, mode of diagnosis (histology, cytology, other), source of information (patient, wife/husband, others), and smoking habits exerted no independent effect. For 35 (57%) cases, occupational exposure was related to asbestos pollution of the workplace and not to the specific work task. Cases with definite, probable, and possible occupational exposure showed no significant difference in the distribution (Kruskal-Wallis test) by year of initial employment at risk, duration of exposure, and latency (median, 36 years). Occupational exposure occurred in a total of 22 workplaces. Three of these accounted for 21 (34%) cases. Multiple (> or = 2) cases (total 27 or 44%) were observed in six workplaces. 相似文献
87.
Assessment of the mutagenicity of dichloroacetic acid in lacI transgenic B6C3F1 mouse liver 总被引:2,自引:0,他引:2
Dichloroacetic acid (DCA) is a chlorination byproduct found in finished
drinking water. When administered in drinking water this chemical has been
shown to produce hepatocellular adenomas and carcinomas in B6C3F1 mice over
the animal's lifetime. In this study, we investigated whether mutant
frequencies were increased in mouse liver using treatment protocols that
yielded significant tumor induction. DCA was administered continuously at
either 1.0 or 3.5 g/l in drinking water to male transgenic B6C3F1 mice
harboring the bacterial lacI gene. Groups of five or six animals were
killed at 4, 10 or 60 weeks and livers removed. At both 4 and 10 weeks of
treatment, there was no significant difference in mutant frequency between
the treated and control animals at either dose level. At 60 weeks, mice
treated with 1.0 g/l DCA showed a 1.3-fold increase in mutant frequency
over concurrent controls (P = 0.05). Mice treated with 3.5 g/l DCA for 60
weeks had a 2.3-fold increase in mutant frequency over the concurrent
controls (P = 0.002). The mutation spectrum recovered from mice treated
with 3.5 g/l DCA for 60 weeks contained G:C-->A:T transitions (32.79%)
and G:C-->T:A transversions (21.31%). In contrast, G:C-->A:T
transitions comprised 53.19% of the recovered mutants among control
animals. Although only 19.15% of mutations among the controls were at T:A
sites, 32.79% of the mutations from DCA-treated animals were at T:A sites.
This is consistent with the previous observation that the proportion of
mutations at T:A sites in codon 61 of the H-ras gene was increased in
DCA-induced liver tumors in B6C3F1 mice. The present study demonstrates
DCA-associated mutagenicity in the mouse liver under conditions in which
DCA produces hepatic tumors.
相似文献
88.
P. Dervanian L. Macé T.A. Folliguet A. di Virgilio J.M. Grinda J.F. Fuzellier B. De Geeter P. Morville J.Y. Neveux 《Pediatric cardiology》1998,19(4):369-373
The prognosis of Marfan syndrome in both adult and pediatric patients is primarily related to the cardiovascular complications.
In infantile Marfan syndrome, although involvement of the mitral valve is the most frequently encountered cardiovascular lesion,
the aortic root can be more worrisome because of its excessive dilatation, leading to aortic insufficiency or dissection.
If the role of elective surgery is relatively well defined for adult patients, it is still debated during childhood. We report
two patients, aged 22 months and 5 years, each presenting an aortic root aneurysm related to Marfan syndrome, and each treated
with the Bentall procedure without specific age-related mortality or morbidity. These two patients experienced normal growth
and were free of any complication for a follow-up period of 8 and 2 years, respectively. More than an absolute value of the
aortic root dimension, it is the conjunction of the rate of progression of the aortic root dilatation, the degree and the
duration of the aortic valve regurgitation, and its resulting left ventricular dysfunction that must be taken into consideration
in choosing the surgical option. 相似文献
89.
Early ovarian cancer: Is there a role for systematic pelvic and para-aortic lymphadenectomy? 总被引:1,自引:0,他引:1
Baiocchi Raspagliesi Grosso Fontanelli Cobellis di Re & di Re 《International journal of gynecological cancer》1998,8(2):103-108
Baiocchi G, Raspagliesi F, Grosso G, Fontanelli R, Cobellis L, di Re E, di Re F. Early ovarian cancer: Is there a role for systematic pelvis and para-aortic lymphadenectomy? Int J Gynecol Cancer 1998; 8 : 103–108.
In order to focus on the incidence and the clinical significance of lymphatic spread in patients with cancer apparently confined to the ovaries, we present our 20 year experience in a large series of patients with early ovarian cancer who had systematic pelvic and para-aortic lymphadenectomy. A retrospective study of 280 consecutive patients is presented. Systematic pelvic and para-aortic lymphadenectomy was performed in 205 cases (73.2%). Selective sampling and node biopsy were performed in 30 (10.7%) and 7 (2.5%), respectively. Node metastases were found in 32/242 patients (13.2%). The incidence of metastatic nodes was significantly higher in patients with serous adenocarcinomas and/or poorly-differentiated tumors. When few nodes were involved (1–3) lymphatic spread was most ipsilateral to the tumor. Even though the retrospective nature of the study has to be considered, univariate analysis revealed statistically significant differences in 5-year survival based on FIGO stage, histology, grade of differentiation, and node status. By contrast, using multivariate analysis, none of these risk factors was an independent variable for predicting long-term survival. However, node status closely approached the statistically significant level ( P = 0.06). Only prospective and randomized studies can clarify the role of lymphadenectomy in early ovarian cancer. However, while awaiting these results, this surgical procedure should be a part of a research protocol. 相似文献
In order to focus on the incidence and the clinical significance of lymphatic spread in patients with cancer apparently confined to the ovaries, we present our 20 year experience in a large series of patients with early ovarian cancer who had systematic pelvic and para-aortic lymphadenectomy. A retrospective study of 280 consecutive patients is presented. Systematic pelvic and para-aortic lymphadenectomy was performed in 205 cases (73.2%). Selective sampling and node biopsy were performed in 30 (10.7%) and 7 (2.5%), respectively. Node metastases were found in 32/242 patients (13.2%). The incidence of metastatic nodes was significantly higher in patients with serous adenocarcinomas and/or poorly-differentiated tumors. When few nodes were involved (1–3) lymphatic spread was most ipsilateral to the tumor. Even though the retrospective nature of the study has to be considered, univariate analysis revealed statistically significant differences in 5-year survival based on FIGO stage, histology, grade of differentiation, and node status. By contrast, using multivariate analysis, none of these risk factors was an independent variable for predicting long-term survival. However, node status closely approached the statistically significant level ( P = 0.06). Only prospective and randomized studies can clarify the role of lymphadenectomy in early ovarian cancer. However, while awaiting these results, this surgical procedure should be a part of a research protocol. 相似文献
90.
Joseph OngrÁdi Steven Specter Attila HorvÁth Herman Friedman 《Pathology oncology research : POR》1998,4(3):191-199
Both marijuana and retroviruses impair natural killer (NK) cell functions, but no data on their simulataneous effects are
available. Similarities to human AIDS induced by Friend leukemia complex (FLO and its helper Rowson-Parr virus (RPV) provides
a mouse model to study drug-virus action. Leukemia susceptible BALB/c and resistant C57BL/6 mice were infected, then at time
intervals their nylon wool-separated splenocytes were exposed to tetrahydrocannabinol (THC) for 3h. Natural killer cell activity
against Yac-1 cells was assayed by 51Cr-release for 4 and 18h. Recovery of splenocytes was found to be suppressed by FLC,
but in BALB/c only by RPV. After a transient enhancement in C57BL/6 by FLC, NK cell activity of both mice became suppressed
early (2 to 4 days), normalized subsequently and enhanced late (11 to 14 days) postinfection. A moderate increase in BALB/c,
no change in C57BL/6 were induced by low (1-2.5 g/ml) THC doses. NK cell activity of BALB/c became suppressed exponentially
by higher (5-10 g/ ml) THC doses in 18h as compared to 4h assays, while its proportional and moderate impairment was seen
in C57BL/6. The magnitude of NK cell activity of infected mice was determined by THC: enhancement or impairment followed those
of untreated, infected counterparts on the level of THC-treated cells. Low doses hardly, high doses additively influenced
NK cells of infected BALB/c. THC slightly affected very early and late enhancement in NK cell activity of FLC infected C57BL/6,
but augmented RPV induced suppression late in 18h assays. Genetic factors similar to endotoxin resistance, altered cytokine
profile might determine these effects. Similar phenomena in humans might result in earlier manifestation of AIDS. 相似文献