全文获取类型
收费全文 | 10576篇 |
免费 | 970篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 81篇 |
儿科学 | 243篇 |
妇产科学 | 280篇 |
基础医学 | 1540篇 |
口腔科学 | 266篇 |
临床医学 | 1218篇 |
内科学 | 2441篇 |
皮肤病学 | 86篇 |
神经病学 | 813篇 |
特种医学 | 423篇 |
外科学 | 1276篇 |
综合类 | 187篇 |
一般理论 | 6篇 |
预防医学 | 1296篇 |
眼科学 | 109篇 |
药学 | 732篇 |
中国医学 | 4篇 |
肿瘤学 | 553篇 |
出版年
2021年 | 142篇 |
2020年 | 94篇 |
2019年 | 142篇 |
2018年 | 163篇 |
2017年 | 103篇 |
2016年 | 156篇 |
2015年 | 150篇 |
2014年 | 258篇 |
2013年 | 325篇 |
2012年 | 456篇 |
2011年 | 526篇 |
2010年 | 299篇 |
2009年 | 248篇 |
2008年 | 504篇 |
2007年 | 462篇 |
2006年 | 459篇 |
2005年 | 435篇 |
2004年 | 372篇 |
2003年 | 354篇 |
2002年 | 342篇 |
2001年 | 321篇 |
2000年 | 321篇 |
1999年 | 294篇 |
1998年 | 128篇 |
1997年 | 103篇 |
1996年 | 120篇 |
1995年 | 92篇 |
1994年 | 78篇 |
1992年 | 272篇 |
1991年 | 247篇 |
1990年 | 243篇 |
1989年 | 228篇 |
1988年 | 224篇 |
1987年 | 192篇 |
1986年 | 221篇 |
1985年 | 194篇 |
1984年 | 188篇 |
1983年 | 179篇 |
1982年 | 124篇 |
1981年 | 101篇 |
1980年 | 85篇 |
1979年 | 158篇 |
1978年 | 122篇 |
1977年 | 107篇 |
1976年 | 95篇 |
1975年 | 80篇 |
1974年 | 110篇 |
1973年 | 105篇 |
1972年 | 87篇 |
1968年 | 88篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
The thesis of this article is that deficits in language and communication contribute to behavior problems in childhood. Mentally retarded children show a range of deficits in language and communication compared with normals; they are also at increased risk for behavior problems. The evidence suggests that these deficits are quantitative rather than qualitative. In addition, these linguistic deficits may contribute independently to the development of behavior disorders insofar as the linguistic deficit interferes with the child's ability to make himself understood or to understand others. 相似文献
4.
S L Peterson 《Brain research bulletin》1991,26(1):43-47
This study evaluates the glycine potentiation of anticonvulsant drugs in subcutaneous pentylenetetrazol seizures in rats. Administered alone, glycine (30 or 40 mM/kg, PO) induced no anticonvulsant effect or neurological deficit. Coadministered with anticonvulsants, glycine significantly enhanced the anticonvulsant potency of diazepam and sodium valproate without affecting the neurological deficit induced by the anticonvulsants. Glycine did not significantly alter the anticonvulsant activity of ethosuximide or phenobarbital. These findings indicate a possible glycine-sensitive component in the mechanism of action of diazepam and sodium divalproate in subcutaneous pentylenetetrazol seizures. With the possible exception of sodium valproate, the present study provides little support for a glycine and gamma-aminobutyric acid (GABA) interaction as a mechanism of anticonvulsant activity in SC PTZ seizures. Further studies are required to determine the role of strychnine-sensitive and strychnine-insensitive glycine receptors in this experimental model of absence epilepsy. 相似文献
5.
The role of CD4+ helper T cells in the destruction of microencapsulated islet xenografts in nod mice 总被引:4,自引:0,他引:4
C J Weber S Zabinski T Koschitzky L Wicker R Rajotte V D'Agati L Peterson J Norton K Reemtsma 《Transplantation》1990,49(2):396-404
Islet transplants for large numbers of patients with diabetes will require xenografts. Microencapsulation is an appealing method for islet xenografting. However, graft function has been limited by a cellular reaction, particularly intense in spontaneously diabetic, NOD mice. The purpose of this study was to elucidate the mechanism of this reaction. Poly-1-lysine-alginate microcapsules containing 4000-12,000 dog or 1800-2000 rat islets were xenografted intraperitoneally into streptozotocin (SZN)-diabetic C57BL/6J and NOD mice, with or without recipient treatment with GK 1.5 (anti-CD4 monoclonal antibody) (20-30 microliters i.p. every 5 days, begun on day -7. Grafts were considered technically successful if random blood glucose (BG) was normalized (less than 150 mg/dl) within 36 hr. Graft failure was defined as BG greater than 250 mg/dl. Dog and rat islets in microcapsules normalized BG in both SZN and NOD mice within 24 hr routinely. Empty microcapsules and GK 1.5 treatments alone did not affect BG. NODs destroyed both microencapsulated dog and rat islets more rapidly than did SZN-diabetic mice (P less than .01). Graft biopsies showed an intense cellular reaction, composed of lymphocytes, macrophages and giant cells, and no viable islets. GK 1.5 treatment significantly prolonged both dog-to-NOD and rat-to-NOD grafts (P less than 0.01). Biopsies of long-term functioning grafts (on days 65-85) demonstrated viable islets and no cellular reaction around microcapsules; 1/4 rat and 1/8 dog islet xenografts continued to function indefinitely in NOD recipients, even after cessation of GK 1.5 therapy. Prediabetic NODs receiving encapsulated dog or rat islets mounted a moderate cellular reaction to grafts. Empty microcapsules excited no cellular reaction in diabetic or prediabetic NODs. We conclude that the NOD reaction to microencapsulated xenogeneic islets is helper T cell-dependent, and that the target of this reaction is not the microcapsule itself, but the donor cells within. 相似文献
6.
H A Peterson 《Orthopedics》1992,15(7):799-808
Physeal injuries of the distal humerus comprise approximately 10% of all physeal injuries. Diagnosis of these injuries at a young age before the ossification centers have ossified and become visible radiographically is difficult. Poor outcome of distal humeral physeal injuries is not uncommon and can be best prevented by knowledge of anatomy and the use of all appropriate imaging techniques. The focus of this article is to correlate anatomy at different ages with the occurrence of specific injuries. 相似文献
7.
Nonvoluntary sexual activity among adolescents 总被引:3,自引:0,他引:3
Data from the 1987 round of the National Survey of Children indicate that seven percent of Americans aged 18-22 have experienced at least one episode of nonvoluntary sexual intercourse. Women were more likely than men to report having had such an experience, with just under half of all nonvoluntary experiences among women occurring before the age of 14. Multiple classification analysis reveals that white women who had lived apart from their parents before age 16, those who had been brought up in poverty, those who had had a physical, emotional or mental limitation when they were young, those whose parents had been heavy drinkers, those whose parents had used illegal drugs and those whose parents had smoked cigarettes when they themselves were teenagers were at significantly greater risk for experiencing sexual abuse. Six percent of young white women with no risk factors, nine percent of those with one, 26 percent of those with two, and 68 percent of those with three or more had been sexually abused before or during adolescence. 相似文献
8.
9.
Alfred E Buxton Hugh Calkins David J Callans John P DiMarco John D Fisher H Leon Greene David E Haines David L Hayes Paul A Heidenreich John M Miller Athena Poppas Eric N Prystowsky Mark H Schoenfeld Peter J Zimetbaum Paul A Heidenreich David C Goff Frederick L Grover David J Malenka Eric D Peterson Martha J Radford Rita F Redberg 《Journal of the American College of Cardiology》2006,48(11):2360-2396
10.
Abstract: Background : In response to rising cesarean rates, it is reasonable for health care organizations to look to a managed care model as a means of controlling further rate increases. However, little conclusive evidence exists to support this solution. We undertook a study of the Department of Defense health care beneficiary population to assess the impact of enrollment in TRICARE Prime, the Department's managed care health plan, on cesarean delivery rates. Methods : Pooled hospital discharge records from 1999–2002 for live, singleton births were analyzed to calculate primary and repeat cesarean rates for TRICARE Prime and non‐Prime beneficiaries in the military and civilian hospitals that comprise the Department of Defense health care network. Stepwise logistic regression was used to calculate adjusted odds ratios for clinical indicators for each combination of health plan and hospital setting using theχ2difference(p < 0.05)to eliminate nonsignificant variables from the model. Total primary and repeat cesarean rates were compared with primary and repeat cesarean rates for women with no reported clinical complications to account for differences in case mix across subgroups. Statistical significance of the differences calculated for subgroups was assessed usingχ2. Results : Primary cesarean rates were significantly lower for TRICARE Prime enrollees relative to non‐Prime beneficiaries for all race subgroups and three of five age subgroups in military hospitals and four of five age subgroups in civilian hospitals. No significant differences in repeat cesarean rates were observed between Prime and non‐Prime beneficiaries within any race or age subgroup. Breech presentation followed by dystocia, fetal distress, and other complications were significant predictors for primary cesarean. Previous cesarean delivery was the leading predictor for repeat cesarean delivery. Primary and repeat cesarean rates observed for military hospitals were consistently lower than rates observed for civilian hospitals within each health plan type and age group. Conclusions : Enrollment in the managed care health plan was significantly associated with lower risk of primary cesarean delivery relative to membership in other health plans offered to Department of Defense health care beneficiaries. Repeat cesarean rates in this population varied independently of health plan type. Primary cesarean delivery was generally associated with clinical complications, whereas previous cesarean delivery was the strongest indictor for a repeat cesarean delivery. A clear explanation of reduced cesarean rates for Prime enrollees remains elusive, but it is likely that factors beyond individual practitioner decision‐making were at work. 相似文献