全文获取类型
收费全文 | 21619篇 |
免费 | 1316篇 |
国内免费 | 85篇 |
专业分类
耳鼻咽喉 | 299篇 |
儿科学 | 565篇 |
妇产科学 | 357篇 |
基础医学 | 2953篇 |
口腔科学 | 474篇 |
临床医学 | 2373篇 |
内科学 | 4576篇 |
皮肤病学 | 476篇 |
神经病学 | 2004篇 |
特种医学 | 1062篇 |
外国民族医学 | 3篇 |
外科学 | 3283篇 |
综合类 | 195篇 |
一般理论 | 8篇 |
预防医学 | 1298篇 |
眼科学 | 586篇 |
药学 | 1394篇 |
中国医学 | 36篇 |
肿瘤学 | 1078篇 |
出版年
2023年 | 110篇 |
2022年 | 113篇 |
2021年 | 458篇 |
2020年 | 292篇 |
2019年 | 432篇 |
2018年 | 535篇 |
2017年 | 362篇 |
2016年 | 480篇 |
2015年 | 588篇 |
2014年 | 689篇 |
2013年 | 881篇 |
2012年 | 1395篇 |
2011年 | 1387篇 |
2010年 | 846篇 |
2009年 | 751篇 |
2008年 | 1269篇 |
2007年 | 1288篇 |
2006年 | 1213篇 |
2005年 | 1140篇 |
2004年 | 975篇 |
2003年 | 973篇 |
2002年 | 842篇 |
2001年 | 328篇 |
2000年 | 274篇 |
1999年 | 310篇 |
1998年 | 186篇 |
1997年 | 196篇 |
1996年 | 144篇 |
1995年 | 140篇 |
1994年 | 134篇 |
1993年 | 113篇 |
1992年 | 185篇 |
1991年 | 186篇 |
1990年 | 154篇 |
1989年 | 163篇 |
1988年 | 157篇 |
1987年 | 156篇 |
1986年 | 139篇 |
1985年 | 141篇 |
1984年 | 144篇 |
1983年 | 120篇 |
1982年 | 102篇 |
1981年 | 87篇 |
1980年 | 94篇 |
1979年 | 104篇 |
1978年 | 87篇 |
1976年 | 64篇 |
1975年 | 65篇 |
1974年 | 64篇 |
1971年 | 65篇 |
排序方式: 共有10000条查询结果,搜索用时 562 毫秒
41.
Joan Prudic Mark Olfson Steven C Marcus Rice B Fuller Harold A Sackeim 《Neuropsychopharmacology》2004,55(3):301-312
BACKGROUND: Clinical trials indicate that electroconvulsive therapy (ECT) is the most effective treatment for major depression, but its effectiveness in community settings has not been examined. METHODS: In a prospective, naturalistic study involving 347 patients at seven hospitals, clinical outcomes immediately after ECT and over a 24-week follow-up period were examined in relation to patient characteristics and treatment variables. RESULTS: The sites differed markedly in patient features and ECT administration but did not differ in clinical outcomes. In contrast to the 70%-90% remission rates expected with ECT, remission rates, depending on criteria, were 30.3%-46.7%. Longer episode duration, comorbid personality disorder, and schizoaffective disorder were associated with poorer outcome. Among remitters, the relapse rate during follow-up was 64.3%. Relapse was more frequent in patients with psychotic depression or comorbid Axis I or Axis II disorders. Only 23.4% of ECT nonremitters had sustained remission during follow-up. CONCLUSIONS: The remission rate with ECT in community settings is substantially less than that in clinical trials. Providers frequently end the ECT course with the view that patients have benefited fully, yet formal assessment shows significant residual symptoms. Patients who do not remit with ECT have a poor prognosis; this underscores the need to achieve maximal improvement with this modality. 相似文献
42.
T Takahashi B Marcus R G Scheerer M Katz 《American journal of obstetrics and gynecology》1991,164(4):1115-1118
A rabbit cervix preparation designed to evaluate the effects of locally administered substances and those of prelabor contractility on cervical ripening is described. In one experiment, one of the two cervices was exposed to prostaglandin E2 gel and the contralateral cervix was exposed to plain gel. In another experiment, one cervix was completely isolated from prelabor contractility, whereas the contralateral cervix remained intact. Cervical ripening was assessed by measurement of the stretch modulus and rate of creep 2 days later. Treatment with prostaglandin E2 gel and exposure to prelabor contractility resulted in significant unilateral cervical changes, suggesting that at least part of the prostaglandin E2 effect is locally mediated and that spontaneous prelabor contractility may play a role in cervical preparation for labor. Furthermore, because of its simplicity, this animal preparation can be useful in the investigation of the effects of other locally administered substances on cervical ripening. 相似文献
43.
44.
45.
Yanfei L Ma Qingqiang Zeng David W Donley Louis-Georges Ste-Marie J Christopher Gallagher Gail P Dalsky Robert Marcus Erik Fink Eriksen 《Journal of bone and mineral research》2006,21(6):855-864
Transiliac bone biopsies were obtained from 55 women treated with teriparatide or placebo for 12-24 months. We report direct evidence that modeling bone formation at quiescent surfaces was present only in teriparatide-treated patients and bone formation at remodeling sites was higher with teriparatide than placebo. INTRODUCTION: Recombinant teriparatide [human PTH(1-34)], a bone formation agent for the treatment of osteoporosis when given once daily subcutaneously, increases biochemical markers of bone turnover and activation frequency in histomorphometry studies. MATERIALS AND METHODS: We studied the mechanisms underlying this bone-forming action of teriparatide at the basic multicellular unit by the appearance of cement lines, a method used to directly classify surfaces as modeling or remodeling osteons, and by the immunolocalization of IGF-I and IGF-II. Transiliac bone biopsies were obtained from 55 postmenopausal women treated with teriparatide 20 or 40 microg or placebo for 12-24 months (median, 19.8 months) in the Fracture Prevention Trial. RESULTS: A dose-dependent relationship was observed in modeling and mixed remodeling/modeling trabecular hemiosteons. Trabecular and endosteal hemiosteon mean wall thicknesses were significantly higher in both teriparatide groups than in placebo. There was a dose-dependent relationship in IGF-II immunoreactive staining at all bone envelopes studied. The greater local IGF-II presence after treatment with teriparatide may play a key role in stimulating bone formation. CONCLUSIONS: Direct evidence is presented that 12-24 months of teriparatide treatment induced modeling bone formation at quiescent surfaces and resulted in greater bone formation at remodeling sites, relative to placebo. 相似文献
46.
The cause and mechanism of post-carotid endarterectomy hypertension remains unknown. To determine the influence of the sympathetic and renin-angiotensin system, we measured cranial and peripheral plasma levels of catecholamine and renin in patients undergoing carotid endarterectomy. Baseline samples were drawn just before carotid clamping (sample I) and compared with study samples drawn immediately after clamp release (sample II), 2 to 6 hours after surgery (sample III), and then 18 to 24 hours after surgery (sample IV). The patients with post-carotid endarterectomy hypertension had an associated increase of cranial and peripheral norepinephrine levels in the postoperative hypertensive period whereas the patients without post-carotid endarterectomy hypertension did not. This association was most pronounced and statistically significant in cranial samples II (p = 0.032) and III (p = 0.005). Epinephrine and dopamine values did not correlate with post-carotid endarterectomy hypertension. Renin values were higher in cranial than in peripheral samples at time period 2 (p = 0.011), suggestive of a central nervous system Goldblatt phenomenon. However, the renin values did not correlate with post-carotid endarterectomy hypertension. We conclude that post-carotid endarterectomy hypertension is associated with elevated cranial norepinephrine levels, suggestive of a central nervous system sympathomimetic mechanism. Optimal prevention and treatment of this brief but frequently occurring hypertension should include a central-acting sympatholytic agent. 相似文献
47.
48.
49.
Marjolein C. H. van der Meulen Robert Marcus Laura K. Bachrach Dennis R. Carter 《Journal of orthopaedic research》1997,15(3):473-476
We have developed an analytical model of long bone cross-sectional ontogeny in which appositional growth of the diaphysis is primarily driven by mechanical stimuli associated with increasing body mass during growth and development. In this study, our goal was to compare theoretical predictions of femoral diaphyseal structure from this model with measurements of femoral bone mineral and geometry by dual energy x-ray absorptiometry. Measurements of mid-diaphyseal femoral geometry and structure were made previously in 101 Caucasian adolescents and young adults 9–26 years of age. The data on measured bone mineral content and calculated section modulus were compared with the results of our analytical model of cross-sectional development of the human femur over the same age range. Both bone mineral content and section modulus showed good correspondence with experimental measurements when the relationships with age and body mass were examined. Strong linear relationships were evident for both parameters when examined as a function of body mass. 相似文献
50.
n
= 9) should be regarded as a palliative measure. Within a short period, CT-guided aspiration led to recurrence of symptoms
in seven of our patients. Standard treatment of NPHC is fenestration with widest possible excision of the cystic wall, which
can be performed laparoscopically (
n
= 10) or by the conventional surgical mode (
n
= 54). One patient was initially operated by the laparoscopic technique but developed bleeding, which necessitated conversion
to the open mode. Three patients underwent synchronous laparoscopic cholecystectomy. Recurrence rates were similar: 11% in
the laparoscopically treated group and 13% in the group that underwent conventional open surgery. Conventional surgical treatment
was always successful in cases of solitary cysts. However, in cases of multiple cysts measuring more than 5 cm, conventional
surgery was followed by recurrence of symptoms in 26% of patients (7/27), who then had to undergo a second operation. Partial
resection of the liver (
n
= 9) was successfully performed in cases of polycystic disease (
n
= 5) with concomitant enlargement of the organ as well as in cases of large solitary cysts of the left lobe of the liver (
n
= 4). In patients in whom we found that the cysts communicated with the ductal system (
n
= 3), we performed a cystojejunostomy to drain the bile. The complication rate was low. In addition to frequent postoperative
ascites, which necessitated no further intervention, we observed infectious complications in four patients. Twenty patients
(22%) expired during a mean follow-up period of 6.2 years. Interestingly, deaths were frequently associated with malignancy
(11/20). After fenestration of multiple cysts measuring > 5 cm, the patients are at high risk for recurrence. Hence partial
resection of the liver is an excellent therapeutic alternative in selected patients with polycystic disease and massive enlargement
of the organ in whom the disease could not be controlled by simple fenestration. The results of this study show that laparoscopic
fenestration should replace the conventional surgical technique as the gold standard in cases of NPHC because the laparoscopic
technique is less stressful for the patient and is associated with a rate of success similar to that of the conventional technique. 相似文献