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   82088篇
  免费   9033篇
  国内免费   5258篇
耳鼻咽喉   776篇
儿科学   894篇
妇产科学   761篇
基础医学   9039篇
口腔科学   1665篇
临床医学   10759篇
内科学   11346篇
皮肤病学   1021篇
神经病学   3624篇
特种医学   2501篇
外国民族医学   44篇
外科学   8019篇
综合类   15191篇
现状与发展   28篇
一般理论   19篇
预防医学   6638篇
眼科学   2281篇
药学   9137篇
  123篇
中国医学   5606篇
肿瘤学   6907篇
  2025年   29篇
  2024年   1338篇
  2023年   1898篇
  2022年   3798篇
  2021年   4891篇
  2020年   3897篇
  2019年   2991篇
  2018年   3084篇
  2017年   2877篇
  2016年   2545篇
  2015年   4037篇
  2014年   4734篇
  2013年   4339篇
  2012年   6084篇
  2011年   6497篇
  2010年   4671篇
  2009年   3744篇
  2008年   4347篇
  2007年   4160篇
  2006年   3981篇
  2005年   3721篇
  2004年   2694篇
  2003年   2481篇
  2002年   2063篇
  2001年   1752篇
  2000年   1555篇
  1999年   1507篇
  1998年   969篇
  1997年   903篇
  1996年   674篇
  1995年   702篇
  1994年   576篇
  1993年   349篇
  1992年   424篇
  1991年   362篇
  1990年   322篇
  1989年   275篇
  1988年   224篇
  1987年   215篇
  1986年   155篇
  1985年   135篇
  1984年   89篇
  1983年   57篇
  1982年   33篇
  1981年   34篇
  1980年   16篇
  1979年   33篇
  1977年   13篇
  1974年   12篇
  1972年   14篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Geodorum (Orchidaceae) has approximately ten species, and is mainly distributed in tropical Asia. Among them, Geodorum eulophioides Schltr. is of major conservation concern as it has only four known populations, two each found in China and others in Burma. In this study, we developed 18 polymorphic microsatellites markers in G. eulophioides with the number of alleles ranging from two to 17. The expected and observed heterozygosities ranged from 0.046 to 0.918 and from 0.048 to 1.0000, respectively. The cross-species amplification rates for the sympatric G. recurvum (Roxb.) Alston and G. densiflorum (Lam.) Schltr. were 100 and 83.33 %, respectively. These markers developed would be useful for conservation and population genetic studies.  相似文献   
102.
The Chinese water snake Enhydris chinensis is an ovoviviparous colubrid snake distributed in China and Vietnam. It is commonly used in the production of Chinese snake oil, which is known for treating ailments such as fever, joint pain, and headache. It is listed as a vulnerable species according to the China red data book of endangered animals. Specific molecular markers such as mitochondrial DNA and microsatellite loci are helpful for us to get a better understanding of population structure and evolutionary history of the snake and take effective conservation action for this species. Here, we characterize eight polymorphic microsatellite loci isolated from E. chinensis genomic libraries. Forty-seven individuals were collected from Ji’an population in Jiangxi, China. These markers revealed a high degree of genetic diversity (3–10 alleles per locus) and heterozygosity (H O ranged from 0.532 to 0.957, and H E ranged from 0.565 to 0.806). No locus exhibited significant deviations from Hardy–Weinberg equilibrium. There was no evidence of linkage disequilibrium among pairs of loci. The results of this paper will be useful for future study of population structure and genetic diversity of E. chinensis.  相似文献   
103.
Adenosine exerts a key role in analgesia. In the present study, adenosine-induced Ca2+ responses were revealed by using confocal microscopy imaging in the rat dorsal root ganglia (DRG) neurons in vitro. Our results showed that adenosine could evoke increases in the intracellular Ca2+ concentration in the DRG neurons. In addition, by application of selective receptor antagonists, two types of receptors, A1R and A3R, were identified to be involved in the adenosine-induced Ca2+ release from intracellular stores in neurons. Altogether, these results suggest that confocal microscopy imaging combined with fluorescent dyes could help to detect the analgesic-induced ion signaling in single cell.  相似文献   
104.
105.

Purpose

The optimal management of proximal hypospadias remains uncertain. In this study, the surgical outcomes of tubularized incised plate repair (TIP) and transverse island flap (TVIF) onlay urethroplasty in boys with hypospadias were compared.

Methods

A total of 176 patients with proximal hypospadias underwent TIP (n = 83) or TVIF onlay repairs (n = 93) by a single surgeon and were evaluated retrospectively. No patient received a testosterone injection prior to surgery. A retrospective review of their medical records collected data regarding age at surgery, chordee, dorsal plication, hypospadias site, penoscrotal transposition, bifid scrotum, congenital hernia, undescended testis and any postoperative complications, including fistula, recurrent curvature, dehiscence, diverticulum, meatal stenosis and urethral stricture. The pediatric penile perception score (PPPS) was completed by parents to evaluate their perception of cosmetic outcomes.

Results

There was no statistical difference in age or any of the anatomical and clinical features of hypospadias. The median follow-up duration was 22 months (range 12–48 months) and 25 months (14–51 months) for the TIP and TVIF onlay groups, respectively. The overall complication rate in the TVIF onlay group was 21.5 % (20/93), which was higher than 18.1 % (15/83) in the TIP group, but the difference was not statistically significant (P = 0.569). The most common complication was urethrocutaneous fistula, occurring in 9.6 % (8/83) of the TIP group and 10.8 % (10/93) of the TVIF onlay group. There were no significant differences in the rate of any complication and the overall PPPS between the two groups.

Conclusion

TIP and TVIF onlay are clinically equivalent for the repair of proximal hypospadias.  相似文献   
106.

Objective

To evaluated the long-term outcomes of laparoscopic unilateral adrenalectomy for primary aldosteronism (PA) caused by unilateral adrenal hyperplasia (UAH).

Methods

One hundred and sixty-four patients who underwent laparoscopic unilateral adrenalectomy for UAH from January 2004 to December 2011 were entered in this retrospective analysis. Patients demographics, perioperative parameters, and follow-up results were recorded and analyzed statistically.

Results

All 164 cases suffered hypertension with biochemical evidence of hyperaldosteronism prior to operation. Hypokalemia was observed in 52/164 (37.14 %) patients. UAH was proved by multi-slice computed tomography (MSCT). All operations were completed successfully without any conversions or complications. Postoperative pathology confirmed that 164 cases were cortical nodular hyperplasia, of which 4 cases coexist with medullary hyperplasia and 7 with micro-adenoma. At the median follow-up of 48 months, hypertension was cured in 88 (53.7 %) patients, improved in 71 (43.3 %) patients, and refractory in 5 (3.05 %) patients. Hypokalemia and hyperaldosteronism were cured in all patients except re-elevation of blood pressure and plasma aldosterone in two patients 1 month after adrenalectomy.

Conclusions

As an underestimated subtype of PA, UAH is accepted gradually. Laparoscopic unilateral adrenalectomy is nowadays the preferred approach to treat patients with PA caused by UAH. When adrenal venous sampling is not allowed, high-resolution MSCT is a reliable test for lateralization of aldosterone hypersecretion in carefully selected patients and 97 % had either cure or improvement in blood pressure control.  相似文献   
107.
108.

Background

Complete video-assisted thoracoscopic surgery (c-VATS) for left upper lobectomy is difficult due to the branching pattern of the left pulmonary artery.

Objective

Our purpose was to report outcomes of a modified technique of c-VATS left upper lobectomy.

Methods

We retrospectively compared the outcomes of 83 patients with stage I/II non-small-cell lung cancer (NSCLC) who received left upper lobectomy between 2008 and 2011; 32 underwent conventional c-VATS and 50 received modified c-VATS. In the modified procedure, the order in which hilum of lung was treated was from the lingular segmental artery to the superior pulmonary vein to the bronchus, and then finally the pulmonary artery.

Results

The mean patient age was 63.6 ± 8.4 years, and no differences were observed in age, gender, and largest tumor diameter between the two groups. No conversion occurred in either group. The surgical time for modified c-VATS was significantly shorter than that for conventional c-VATS (210 vs. 270 min, p < 0.001). Drainage time after surgery and length of hospitalization for the modified c-VATS group were significantly less than those for the conventional group (drainage 3 vs. 4 days, respectively, p = 0.041; length of hospitalization 7 versus 12 days, respectively; p < 0.001). Surgical margins were clear in all cases. Four (8.0 %) complications occurred in the modified procedure group compared with ten (31.3 %) in the conventional group (p = 0.015).

Conclusion

This new technique offers shorter surgical and postoperative drainage time, shorter hospital stays, and fewer complications than conventional c-VATS upper left lobectomy.  相似文献   
109.

Objective

The extraction of specific data from electronic medical records (EMR) remains tedious and is often performed manually. Natural language processing (NLP) programs have been developed to identify and extract information within clinical narrative text. We performed a study to assess the validity of an NLP program to accurately identify patients with prostate cancer and to retrieve pertinent pathologic information from their EMR.

Materials and methods

A retrospective review was performed of a prospectively collected database including patients from the Southern California Kaiser Permanente Medical Region that underwent prostate biopsies during a 2-week period. A NLP program was used to identify patients with prostate biopsies that were positive for prostatic adenocarcinoma from all pathology reports within this period. The application then processed 100 consecutive patients with prostate adenocarcinoma to extract 10 variables from their pathology reports. The extraction and retrieval of information by NLP was then compared to a blinded manual review.

Results

A consecutive series of 18,453 pathology reports were evaluated. NLP correctly detected 117 out of 118 patients (99.1 %) with prostatic adenocarcinoma after TRUS-guided prostate biopsy. NLP had a positive predictive value of 99.1 % with a 99.1 % sensitivity and a 99.9 % specificity to correctly identify patients with prostatic adenocarcinoma after biopsy. The overall ability of the NLP application to accurately extract variables from the pathology reports was 97.6 %.

Conclusions

Natural language processing is a reliable and accurate method to identify select patients and to extract relevant data from an existing EMR in order to establish a prospective clinical database.  相似文献   
110.
Promoting new bone formation during distraction osteogenesis (DO) in elderly patients with osteoporosis is still a challenge. In this study, we investigated the effect of gene therapy using local Runt‐related gene 2 on new bone formation during osteoporotic mandibular DO in rabbits. First, we successfully established a mandibular osteoporotic animal model by ovariectomizing rabbits. Second, the right mandibles of the osteoporotic rabbits were distracted after corticotomy. The distraction gap of the rabbits in Group A2 and B2 were injected with Adv‐hRunx2‐GFP‐transfected adipose‐derived stromal cells (ADSCs) and Adv‐GFP‐transfected ADSCs, respectively. Rabbits in Groups C2 (ovariectomized control) and D2 (sham surgery control) were injected with physiologic saline. New‐generation bone tissue in the distraction gap was analyzed via plain radiographic examinations, micro‐computed tomography, histological examinations, and biomechanical testing at weeks 3, 6, and 9 of the consolidation period. Results of above examinations showed that no ideal new bone formation was observed in Groups B2 and C2, but obvious ideal new bone formation was observed in Group A2 and D2. The results suggested that gene therapy using rhRunx2‐modified ADSCs promoted new bone formation during osteoporotic mandibular DO and effectively compensated for the detrimental effects of systemic osteoporosis on new bone formation. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:709–720, 2014.  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