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   2071310篇
  免费   165254篇
  国内免费   4803篇
耳鼻咽喉   28953篇
儿科学   65759篇
妇产科学   60135篇
基础医学   295717篇
口腔科学   58082篇
临床医学   184501篇
内科学   405344篇
皮肤病学   46562篇
神经病学   170871篇
特种医学   80586篇
外国民族医学   626篇
外科学   314034篇
综合类   52400篇
现状与发展   4篇
一般理论   706篇
预防医学   163128篇
眼科学   48225篇
药学   148855篇
  1篇
中国医学   4465篇
肿瘤学   112413篇
  2018年   21896篇
  2017年   16813篇
  2016年   19039篇
  2015年   21606篇
  2014年   30706篇
  2013年   46226篇
  2012年   62466篇
  2011年   65926篇
  2010年   38698篇
  2009年   36892篇
  2008年   61379篇
  2007年   65545篇
  2006年   65985篇
  2005年   64155篇
  2004年   61763篇
  2003年   59224篇
  2002年   57179篇
  2001年   96863篇
  2000年   99146篇
  1999年   82857篇
  1998年   24097篇
  1997年   21824篇
  1996年   21766篇
  1995年   20655篇
  1994年   19102篇
  1993年   17914篇
  1992年   64804篇
  1991年   62358篇
  1990年   60313篇
  1989年   57659篇
  1988年   53486篇
  1987年   52363篇
  1986年   49307篇
  1985年   47322篇
  1984年   36338篇
  1983年   30813篇
  1982年   19202篇
  1981年   17340篇
  1979年   34092篇
  1978年   24279篇
  1977年   20280篇
  1976年   18926篇
  1975年   19861篇
  1974年   24370篇
  1973年   23481篇
  1972年   22199篇
  1971年   20358篇
  1970年   19405篇
  1969年   18376篇
  1968年   16961篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
Piroximone (MDL 19,205), a new imidazolone derivative, was given intravenously to 14 patients with congestive heart failure (NYHA class II-III), while under constant daily doses of digitalis and diuretics. In the first 3 patients, we determined the dose safely eliciting a favorable hemodynamic response. The subsequent 11 patients received 1 mg/kg of piroximone intravenously, and the hemodynamic effects were compared with those of sodium nitroprusside (SN) at a dose-lowering mean blood pressure by 10-20 mm Hg. Piroximone increased heart rate (13.2 +/- 2.0 beats/min, mean +/- SEM) and lowered mean arterial pressure (9 +/- 2.3 mm Hg). Both agents reduced similarly wedge pressure (6.5 +/- 2.9 and 9 +/- 2.9 mm Hg, respectively, for SN and piroximone) and total peripheral resistance. Cardiac index was increased less by SN (15%) than piroximone (48%) (p less than 0.001), and stroke work index significantly enhanced only by piroximone (p less than 0.001). The changes in loading conditions induced by the two agents being similar, it is likely that piroximone not only acts by peripheral vasodilation, but also possesses positive inotropic properties. Myocardial oxygen demand, assessed indirectly by tension-time index, was not affected by piroximone. Thus, piroximone appears to combine well-balanced vasodilator and inotropic properties which make this new agent potentially very useful for the management of congestive heart failure.  相似文献   
994.
In the model of genital herpes simplex virus (HSV)-infection of mice, early latency could be induced by passive immunization with HSV-specific antibodies and, to a lesser degree, by adoptive transfer of immune lymphocytes prepared from spleen and draining lymph nodes of genitally infected syngeneic mice. Conversely, spontaneously occurring latency was inhibited by treatment of the animals with cyclophosphamide (Cph) and, to a lesser degree, with cyclosporin A (CyA). Whereas the effect of CyA could be compensated by passively administered HSV-specific antibodies, that of Cph could not. Apparently specific antibodies cooperate with a non-specific proliferating cell type, probably macrophages and/or NK-cells, as could be demonstrated by significantly reduced antibody effect in silica-treated mice. Moreover, F(ab)2 fragments, in contrast to complete antibody molecules, were inactive. HSV-specific antibodies and also immune lymphocytes had little effect on virus production in the mucous membranes, immune lymphocytes being at least as active as antibodies. It is therefore not probable that latency is induced by attenuation of the peripheral disease. It can rather be concluded that the neuron itself is the target for the action of specific antibodies, cooperating in turn with macrophages and/or NK cells.With support of the Deutsche Forschungsgemeinschaft, Schn 174/6-3  相似文献   
995.
Fifty-five patients with vascular insufficiency resulting in above-knee (AK) and through-knee (TK) amputations were studied to determine factors related to prosthetic candidacy and functional outcome. Chart review showed that the only difference between patients who were fitted with prostheses and those who were not fitted with prostheses was their respective number of medical complications. Twenty-three of 31 patients with prostheses were evaluated 7 to 35 months after receiving the prostheses. Ten (44%) of these patients wore their prostheses all day every day and used wheelchairs minimally or not at all. Over half of the patients evaluated used their wheelchairs most of the time. Two (9%) of the 23 patients had stopped wearing their prostheses. Patients who demonstrated increased walking distances and velocities at follow-up used their prostheses more and their wheelchairs less than did the other patients. Neither gait factors nor hip range of motion at discharge was predictive of continued prosthetic use. Functional outcome and prosthetic use were limited in this group of elderly patients with dysvascular AK and TK amputations. The results of this study may serve as a basis for clinical determination of prosthetic candidacy and functional goals.  相似文献   
996.
A goal for the obstetrician and neonatologist is to screen for risk factors associated with intraventricular hemorrhage (IVH) in the low-birthweight infant. Perinatal events that lead to neonatal metabolic and cardiovascular derangements seem to provoke IVH, and conflicting reports have implicated labor as being contributory. A fetal heart rate (FHR) abnormality during premature labor may be a predictor of subsequent neonatal IVH. For this reason, 5 years of FHR tracings at two university medical centers were reviewed for inborn infants who were delivered after premature labor and weighed less than or equal to 2000 gm. Sixty-four infants developed IVH, but pre-existing labor with a discernible FHR pattern was recorded in only 38 (59%) cases. Interpretations were reassuring in 17 (45%) cases, suspicious in 7 (18%) cases, and ominous in 14 (37%) cases. This proportion of FHR patterns was not significantly different from a matched group of premature infants without IVH during the same period. Interpretations of intrapartum FHR patterns of low-birthweight infants are limited, especially before 30 weeks gestation, and not useful in predicting neonatal IVH.  相似文献   
997.
998.
Granuloma annulare possibly triggered by antitetanus vaccination   总被引:4,自引:0,他引:4  
We report the case of a 6-year-old girl with granuloma annulare (GA) possibly related to antitetanus vaccinations. The first episode occurred 2 months after the girl had been vaccinated but the lesions were not located at the vaccination site. After 1 year of being free of lesions, she had a second episode unrelated to vaccination. After another 6-month lesion-free period, the girl was administered another antitetanus vaccination and a solitary lesion developed at the vaccination site within 3 days. A few lesions developed on her legs in the 2 months following the appearance of the initial plaque. The literature includes two reports of cases with papular lesions limited to the hepatitis B vaccination site, both histopathologically consistent with necrobiotic granuloma, but clinically not suggestive of GA. To the best of our knowledge, GA following antitetanus vaccination and occurring at the vaccination site has not been reported before. Either the trauma alone from the injection or a vaccine-induced immunological reaction might have triggered the necrobiosis of collagen through some unexplained mechanisms.  相似文献   
999.
1000.
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