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   25939篇
  免费   1627篇
  国内免费   114篇
耳鼻咽喉   295篇
儿科学   880篇
妇产科学   588篇
基础医学   2901篇
口腔科学   501篇
临床医学   2128篇
内科学   5545篇
皮肤病学   361篇
神经病学   1581篇
特种医学   761篇
外科学   4812篇
综合类   788篇
一般理论   19篇
预防医学   1745篇
眼科学   677篇
药学   2286篇
中国医学   246篇
肿瘤学   1566篇
  2023年   204篇
  2022年   587篇
  2021年   956篇
  2020年   606篇
  2019年   738篇
  2018年   893篇
  2017年   607篇
  2016年   577篇
  2015年   731篇
  2014年   1024篇
  2013年   1314篇
  2012年   1875篇
  2011年   1853篇
  2010年   1069篇
  2009年   838篇
  2008年   1421篇
  2007年   1461篇
  2006年   1381篇
  2005年   1262篇
  2004年   1161篇
  2003年   1029篇
  2002年   857篇
  2001年   636篇
  2000年   564篇
  1999年   455篇
  1998年   180篇
  1997年   134篇
  1996年   137篇
  1995年   151篇
  1994年   89篇
  1993年   102篇
  1992年   246篇
  1991年   234篇
  1990年   191篇
  1989年   209篇
  1988年   163篇
  1987年   172篇
  1986年   144篇
  1985年   154篇
  1984年   127篇
  1983年   101篇
  1982年   64篇
  1981年   81篇
  1979年   107篇
  1978年   73篇
  1977年   76篇
  1975年   63篇
  1974年   57篇
  1973年   61篇
  1972年   56篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
We describe 100 consecutive patients with histologically proven gastric carcinoma who were admitted to various hospitals in Northern Pakistan. Twenty-six per cent of patients were under 40 years of age. In a majority of patients the tumour was of a morphological type associated with poor prognosis. In most cases the disease was already at an advanced stage at the time of diagnosis, and most patients died within one year.  相似文献   
82.
The inhibitory effects of aminobeclamide (N-(p-aminobenzyl)-beta-chloropropionamide) on socially offensive behaviour has been studied and compared with those of the parent drug beclamide (N-benzyl-beta-chloropropionamide). Following oral administration in mice which had been individually housed for a 28 day period then paired with normal group-housed opponents, aminobeclamide and beclamide both produced significant and dose-related inhibition of socially offensive behaviour. Aminobeclamide (20-150 mg kg-1 p.o.) and beclamide (50-250 mg kg-1 p.o.) gave increased offense onset latency whilst at the same time they reduced the incidence of offense encounters/animal and decreased the group percentage of animals displaying offense behaviour. It is likely that both drugs have similar monoamine modifying effects though this animal study suggests that aminobeclamide is 1.5 to 2.7 times more potent than beclamide against socially offensive behaviour.  相似文献   
83.
The antibacterial activity of the volatile oil of Nigella sativa seeds was studied against 37 isolates of Shigella dysenteriae 1, Shigella flexneri, Shigella sonnei and Shigella boydii and 10 strains of Vibrio cholerae and Escherichia coli. Most of the strains were clinically resistant to ampicillin, co-trimoxazole and tetracycline. All the strains tested showed promising sensitivity to the volatile oil. The minimum inhibitory concentration (MIC) of the volatile oil for Shigella, Vibrio and Escherichia strains tested was between 50–400 μg/mL.  相似文献   
84.
85.
We have studied the effect of dietary fish oil supplementation (3.2 gm/day of eicosapentaenoic acid and 2.2 gm/day of docosahexaenoic acid) for 10 weeks on the antigen-induced, cutaneous late-phase response (LPR) in 16 atopic individuals. All subjects developed an LPR to intradermal allergen injection. The mean +/- SEM area of induration at 6 hours was 1840 +/- 472 mm2. A biopsy was performed at the LPR site at 6 hours. Subjects were then randomized to receive fish oil or placebo olive oil in a double-blind, parallel fashion, for 10 weeks. After the diet, there were no significant differences between fish oil and placebo treatment in the size of the immediate wheal-and-flare response or the extent of induration at 4 and 6 hours, as compared with prediet values in each group. Histologically, at 6 hours, there was a significant infiltrate into the allergen site compared with that of the control diluent site of total inflammatory cells (p less than 0.002) as well as of eosinophils (p less than 0.001). However, there were no significant differences when pre- and postdiet values were compared. Hence, we conclude that dietary fish oil supplementation does not inhibit the cutaneous LPR clinically or histologically.  相似文献   
86.
A multicenter, randomized placebo-controlled double-blind trial of nimodipine in poor-grade aneurysm patients was carried out in 17 Canadian hospitals. Of 188 patients enrolled in the trial, 32 were excluded for protocol violations and two were excluded due to statistical considerations, leaving 154 patients for valid outcome analysis. Nimodipine treatment was associated with a significantly better outcome (p less than 0.001): 21 (29.2%) of 72 nimodipine-treated patients had a good outcome at 3 months after subarachnoid hemorrhage (SAH) compared to eight (9.8%) of 82 placebo-treated patients. Delayed ischemic deficits from vasospasm alone were significantly less frequent in the nimodipine group (p less than 0.05) with permanent deficits occurring in five nimodipine-treated patients (6.9%) and in 22 placebo-treated patients (26.8%). Improvement in the good outcome rate and reduction in delayed ischemic deficits from vasospasm alone occurred in both Grade 3 and 4 patients, with no difference between nimodipine- and placebo-treated patients being found in Grade 5 patients. Repeat angiography after Day 4 was carried out in 124 patients. There was no significant difference in the incidence of moderate or severe diffuse spasm, which was seen in 64.3% of nimodipine-treated patients and 66.2% of placebo-treated patients. The authors conclude that nimodipine treatment in poor-grade patients with SAH results in an increase in the number of good outcomes and a reduction in the incidence of delayed neurological deterioration due to vasospasm. This effect occurs by a mechanism other than prevention of large-vessel spasm as visualized on angiography.  相似文献   
87.
The feasibility of spindle afferent recording during naturally or electrically induced hindlimb movements is demonstrated in the case of spinalized, decapitated turtles. Since these recordings are obtained from fine filaments of exposed dorsal roots, it is possible for the experimenter to select the afferents of interest. This feasibility, together with the fact that spinally generated movements are readily exhibited, make the turtle an attractive animal for the study of spinal motor control mechanisms.  相似文献   
88.
Eleven mammalian toll-like receptors (TLRs 1–11) have been identified to date and are known to play a crucial role in the regulation of immune responses; however, the factors that regulate TLR expression and function in vivo are poorly understood. Therefore, in the present study, we investigated the physiological regulation of TLR expression and function in humans. To examine the influence of diurnal rhythmicity on TLR expression and function, peripheral venous blood samples were collected from healthy volunteers ( n = 8) at time points coinciding with the peak and nadir in the endogenous circulating cortisol concentration. While no diurnal rhythmicity in the expression of TLRs 1, 2, 4 or 9 was observed, the upregulation of costimulatory (CD80 and CD86) and antigen-presenting (MHC class II) molecules on CD14+ monocytes following activation with specific TLR ligands was greater ( P < 0.05) in samples obtained in the evening compared with the morning. To examine the influence of physical stress on TLR expression and function, peripheral venous blood samples were collected from healthy volunteers ( n = 11) at rest and following 1.5 h of strenuous exercise in the heat (34°C). Strenuous exercise resulted in a decrease ( P < 0.005) in the expression of TLRs 1, 2 and 4 on CD14+ monocytes. Furthermore, the upregulation of CD80, CD86, MHC class II and interleukin-6 by CD14+ monocytes following activation with specific TLR ligands was decreased ( P < 0.05) in samples obtained following exercise compared with at rest. These results demonstrate that TLR function is subject to modulation under physiological conditions in vivo and provide evidence for the role of immunomodulatory hormones in the regulation of TLR function.  相似文献   
89.
OBJECTIVE: Iatrogenic Oesophageal perforations are a dreaded complication and there is no consensus as to their best management. The aim of our study was to assess the results of conservative management in these cases. METHODS: Twenty-six patients with iatrogenic perforations of the oesophagus treated over a 10-year period were reviewed retrospectively. They were managed conservatively by keeping them nil by mouth on intravenous fluids and intravenous antibiotics. Out of these 26, nine were patients of carcinoma of the oesophagus while the remaining 17 had benign pathologies. Twenty-two were diagnosed within 6h, while the remaining four were diagnosed over 24h after perforation. Twenty-three of the 26 were caused by oesophageal dilatations. RESULTS: Twenty-two (84.6%) of the 26 survived on this regimen. Out of the four that died, two had advanced carcinomas and died of chest complications, one died of a myocardial infarction and the fourth was an old debilitated man who died of renal failure. All four who died had extension of the leak into the pleural cavity. Early diagnosis and treatment is of critical importance and is only possible by maintaining a high index of suspicion. CONCLUSIONS: Conservative management when applied to cases of iatrogenic oesophageal perforations gives results comparable to or better that those reported in series where early surgical intervention was practised. Extension of the leak into the pleura carries a worse prognosis.  相似文献   
90.
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