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   4532篇
  免费   404篇
  国内免费   4篇
耳鼻咽喉   75篇
儿科学   129篇
妇产科学   80篇
基础医学   714篇
口腔科学   69篇
临床医学   471篇
内科学   734篇
皮肤病学   78篇
神经病学   493篇
特种医学   264篇
外科学   709篇
综合类   56篇
一般理论   3篇
预防医学   381篇
眼科学   119篇
药学   254篇
中国医学   31篇
肿瘤学   280篇
  2021年   70篇
  2020年   41篇
  2019年   79篇
  2018年   95篇
  2017年   52篇
  2016年   56篇
  2015年   85篇
  2014年   108篇
  2013年   205篇
  2012年   219篇
  2011年   250篇
  2010年   127篇
  2009年   110篇
  2008年   195篇
  2007年   214篇
  2006年   217篇
  2005年   215篇
  2004年   222篇
  2003年   193篇
  2002年   183篇
  2001年   112篇
  2000年   99篇
  1999年   108篇
  1998年   47篇
  1997年   46篇
  1996年   58篇
  1995年   50篇
  1994年   39篇
  1993年   30篇
  1992年   71篇
  1991年   73篇
  1990年   69篇
  1989年   64篇
  1988年   83篇
  1987年   71篇
  1986年   73篇
  1985年   59篇
  1984年   55篇
  1983年   37篇
  1982年   36篇
  1981年   26篇
  1980年   32篇
  1979年   54篇
  1978年   45篇
  1975年   40篇
  1973年   39篇
  1972年   37篇
  1968年   26篇
  1967年   30篇
  1966年   25篇
排序方式: 共有4940条查询结果,搜索用时 757 毫秒
11.
12.
Panic disorder is a chronic and disabling condition that is often accompanied by other psychiatric and medical conditions. The serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) have been used effectively with panic disorder (PD) and conditions in which panic attacks frequently occur. Escitalopram is the most selective SSRI and a variety of evidence suggests it is of great value in the treatment of panic disorder. In this paper, we review the theoretical and practical implications of its use.  相似文献   
13.
14.
C2H2-type zinc finger genes comprise one of the largest genefamilies in the human genome. These proteins are involved ingenetic regulation and development and are quite conserved throughoutevolution. The finger domains commonly contain the small linkerpeptide TGEKP between some finger units. Here, we report theisolation of 133 human zinc finger cDNAs, of which 118 are novel.These clones were isolated from human brain cDNA libraries usingoligonucleotide hybridization followed by expressed sequencetag (EST) analysis, sequencing from the conserved linker regionusing degenerate oligonucleotide primers. This directed partialsequencing approach to cDNA isolation and characterization,signature sequencing, combines the speed of EST automatic sequencingwith the focus of specific cDNA family analysis. Signature sequencingminimizes the generation of less informative random EST sequencesand provides a unique relative position for sequence comparison.We also show that there is an even distribution of these RNA5from this brain cDNA library, and that these cDNAs contain N-terminaldomains found in other zinc finger genes. This rapid focusedsequencing approach should be applicable to any family of cDNAscontaining short conserved signature peptide sequences.  相似文献   
15.
Monolayer cultures of 12-day chick embryo chondrocytes from the regions of dividing (zone 1), elongated (zone 2), and hypertrophied (zone 3) chondrocytes in the tibial cpiphyseal growth plate were analyzed for their capacity to synthesize types II, IX, X, and XI collagens. Synthesis of types II and IX collagens was markedly elevated in the zone 2 culture, while type X collagen synthesis was maximal in zone 3. Type XI collagen was synthesized at low rates in all cultures, with some elevation of its rate in zones 2 and 3. In terms of mol percent of total collagen synthesis, types II and IX collagens decreased from zone 1 to zone 3, while type X collagen increased progressively. Thus, the composition of the extracellular collagens produced by the different zones changed markedly during chondrocyte differentiation. In addition, type X collagen was released exclusively into the culture medium, whereas type XI collagen was retained in the extracellular cell-associated matrix. In contrast, types II and IX collagens were found in both the culture medium and the cell matrix pools. Although types II and IX collagens showed similar changes during differentiation, the synthetic molar ratios of these two collagens varied from 3 to 18 in different cultures, suggesting that the synthesis of these two products is not tightly coupled in these cells.  相似文献   
16.
We analyzed the changes in lateral ligament forces during anterior drawer and talar tilt testing and examined ankle joint motion during testing, following an isolated lesion of the anterior talofibular ligament (ATFL) or a combined lesion of the ATFL and calcaneofibular ligament (CFL). 8 cadaver specimens were held in a specially designed testing apparatus in which the ankle position (dorsiflexion-plantarflexion and supination-pronation) could be varied in a controlled manner. Ligament forces were measured with buckle transducers, and joint motion was measured with an instrumented spatial linkage. An anterior drawer test was performed using an 80 N anterior translating force, and a talar tilt test was performed using a 5.7 Nm supination torque with intact ligaments, after sectioning of the ATFL, and again after sectioning of the CFL. The tests were repeated at 10° dorsiflexion, neutral, and 10° and 20° plantarflexion. In the intact ankle, the largest increases in ATFL force were observed during testing in plantarflexion, whereas the largest increases in CFL force were observed in dorsiflexion. Isolated ATFL injury caused only small laxity changes, but a pronounced increase in laxity was observed after a combined CFL and ATFL injury.  相似文献   
17.
Although major tissue trauma produces profound depression of cell-mediated immunity, it is not known whether surgical trauma (i.e., midline laparotomy) has any adverse effect on the antigen presentation function and membrane interleukin-1 (IL-1) activity of peritoneal macrophages. To study this, C3H/HEJ (endotoxin-tolerant) mice were anesthetized. An approximately 1-inch midline abdominal incision was made, followed by abdominal closure. On days 1, 3, 5, and 7, peritoneal macrophages were harvested by means of peritoneal lavage, and antigen presentation capability was tested by incubating various numbers of peritoneal macrophages with 2 X 10(4) D10.G4.1 cells per well in the presence of conalbumin (400 micrograms/ml). The T helper cell clone (D.10.G4.1) proliferates on recognition of conalbumin in the context of Iak and also proliferates in the presence of membrane-bound IL-1 plus concanavalin A. To measure membrane IL-1 expression in peritoneal macrophages, Concanavalin A (10 micrograms/ml) was substituted for conalbumin. Cultures were incubated for 72 hours, pulsed with tritiated thymidine, and harvested. Peritoneal macrophages from laparotomized mice induced significantly less T helper cell proliferation on days 1 and 3 in the antigen presentation assay (37% and 30%, respectively; p less than 0.05) and in the membrane IL-1 assay (14% and 10%, respectively; p less than 0.05) as compared with the control. This difference was not detectable on day 5. More effective antigen presentation capability (167% of control; p less than 0.05) was seen on day 7. Thus laparotomy by itself produces marked depression of both antigen presentation function and membrane IL-1 activity of peritoneal macrophages, which may enhance susceptibility to intra-abdominal sepsis.  相似文献   
18.
The purpose of this investigation was to determine if there was any relationship between dietary carnitine intake and the concentrations of carnitine in skeletal muscle and blood plasma in healthy adult men and women. Subjects (14 men, 14 women, fasted 8 h) reported to the Biodynamics Laboratory where they completed a 24-h diet recall questionnaire. Resting muscle biopsy (vastus lateralis) and blood plasma samples were taken and assayed for free, short-chain, and long-chain acyl carnitine concentrations. Dietary carnitine intake was estimated from data on concentrations in food. There was no significant relationship between either protein or carnitine intake with skeletal muscle carnitine concentrations. There was a significant relationship between both dietary carnitine (r = 0.50) and protein (r = 0.48) intake with blood plasma total acid soluble carnitine concentrations (p less than 0.01) in all subjects.  相似文献   
19.
Background: The occurrence of benign bone cysts adjacent to an active physis may be associated with a physeal arrest. That arrest may result from physeal penetration of the cysts itself, secondary pathologic fracture or the result of surgical curettage. Methods : The pre-treatment X-rays of patients attending the Bone Tumor Clinic at the Children's Hospital and Medical Center were reviewed. Those patients presenting with a bone cyst were identified and the affected side was compared to the normal side in order to determine growth discrepancies. Results: Three cases of benign bone cysts are presented that were located adjacent to a growing physis and produced growth disturbance in the absence of surgical intervention. Conclusions: The risk of growth disturbance in itself should not be a contraindication to surgical intervention.  相似文献   
20.
Three patients with mycosis fungoides, who were long-term employees of a manufacturer of solid fuel propellants, were seen. Two of these patients had tumorous involvement of the central nervous system, which was successfully treated with radiation therapy. The potential relationship of carcinogens is discussed.  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