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   25366篇
  免费   1210篇
  国内免费   204篇
耳鼻咽喉   172篇
儿科学   639篇
妇产科学   213篇
基础医学   3129篇
口腔科学   400篇
临床医学   1569篇
内科学   6829篇
皮肤病学   420篇
神经病学   1973篇
特种医学   1174篇
外科学   4240篇
综合类   100篇
预防医学   672篇
眼科学   320篇
药学   1584篇
中国医学   46篇
肿瘤学   3300篇
  2023年   196篇
  2022年   358篇
  2021年   641篇
  2020年   318篇
  2019年   500篇
  2018年   612篇
  2017年   479篇
  2016年   616篇
  2015年   638篇
  2014年   881篇
  2013年   1003篇
  2012年   1589篇
  2011年   1776篇
  2010年   994篇
  2009年   839篇
  2008年   1452篇
  2007年   1657篇
  2006年   1655篇
  2005年   1652篇
  2004年   1624篇
  2003年   1552篇
  2002年   1518篇
  2001年   370篇
  2000年   284篇
  1999年   328篇
  1998年   364篇
  1997年   307篇
  1996年   287篇
  1995年   236篇
  1994年   211篇
  1993年   191篇
  1992年   204篇
  1991年   197篇
  1990年   147篇
  1989年   141篇
  1988年   138篇
  1987年   90篇
  1986年   101篇
  1985年   98篇
  1984年   85篇
  1983年   68篇
  1982年   53篇
  1981年   46篇
  1980年   28篇
  1979年   31篇
  1978年   28篇
  1977年   21篇
  1974年   18篇
  1973年   19篇
  1971年   16篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
Summary Cranial computed tomography (CT) of 108 cases with dilated lateral ventricles was reviewed to elucidate the relationship between focal vulnerability of developing brain and disproportional dilatation of lateral ventricles. CT findings of 108 cases with symmetrical dilatation of lateral ventricles were classified into three types by morphometry of lateral ventricles: anterior horn predominant type (31 cases), diffuse type (36 cases), posterior horn predominant type (41 cases). Posterior horn predominant type has a tendency to occur in congenital anomalies and premature brain damage, and anterior horn predominant type in infantile brain damage. This disproportional dilatation of anterior or posterior horns suggests a vulnerability of periventricular structure in developing brain.  相似文献   
12.
13.
In this study, we used a novel 4-fluid nozzle spray drier to prepare composite microparticles of a water-insoluble drug, flurbiprofen (FP), and a water-soluble drug, sodium salicylate (SS), for the purpose of improving the water solubility of FP. An ethanol solution of FP and an aqueous SS solution were simultaneously introduced through different liquid passages in the 4-fluid nozzle spray drier and then spray-dried. Quantitative elemental analysis suggested that the FP/SS ratio in each composite microparticle was nearly the same as the formulation ratio. We also found that SS and FP exist in a low crystallinity state in the composite particles. Release of FP from dissolved composite microparticles was markedly improved because of an increase in the effective surface area following rapid dissolution of SS. This study shows that it is possible to prepare FP-SS composite microparticles using a 4-fluid nozzle spray drier in single process and that this can improve the ability of FP to dissolve in water.  相似文献   
14.
BACKGROUND: To understand the immunopathological features of oral lichen planus (OLP), we analyzed the expression of chemokines in the epithelial cell layers. Methods: Epithelia from OLP or healthy gingiva were collected by laser microdissection. The chemokine and chemokine receptor expressions in the epithelia were analyzed by DNA microarray. RESULTS: High levels of MIP-3alpha/LARC/CCL20 and its receptor CCR6 were expressed in the lesional epithelia. Furthermore, DC-CK1/CCL18, ELC/CCL19, SDF-1/CXCL12 and CXCR4 expressions were also increased. Immunohistologial analysis showed that high numbers of Langerhans cells (LCs) were present in the epithelia of OLP. Lesional epithelia also expressed high levels of the ligands specific for CXCR3 (e.g. MIG/CXCL9, IP-10/CXCL10 and I-TAC/CXCL11) and CCR5 (e.g. RANTES/CCL5). CONCLUSIONS: Infiltration of LCs is orchestrated by CCR6. Further, LCs residing in the lesional epithelia may be a mature phenotype. Moreover, infiltration of T cells in OLP could be mediated by signaling pathways through CXCR3 and CCR5.  相似文献   
15.
OBJECTIVE: Tubularized incised plate urethroplasty has become a popular technique for repairing distal and proximal hypospadias in many institutions. Dorsal inlay graft urethroplasty has been used in our institution since 2003 to reduce the risk of meatal stenosis. In the present study, we evaluated the results of the dorsal inlay graft procedure. METHODS: A total of 28 patients with no deep groove and no severe curvature underwent one-stage urethroplasty using an inner preputial-based dorsal inlay graft. The medical records of all patients were retrospectively reviewed with regard to complication rate and cosmetic appearance. RESULTS: Mean patient age at surgery was 21 months (range, 14 months to 4.6 years). Preoperatively the urethral meatus was coronal in two cases, distal shaft in 17, proximal shaft in six and penoscrotal in three. Nine patients required testosterone therapy before surgery. Mean operative time was 200 min (range, 154-249 min). Mean length of inlay graft was 20.9 mm (range, 12-30 mm). In all patients, a straight penis was achieved without dorsal plication of the corposa cavernosa, and the neomeatus with a slit-like appearance was positioned at the glans tip. At a mean of 22 months of follow up, a urethrocutaneous fistula developed in only one patient (3.6%), requiring repair surgery 6 months after urethroplasty. No patient had meatal stenosis, neourethral stricture or urethral diverticulum along the inlay graft. CONCLUSION: Dorsal inlay graft urethroplasty is an effective method for hypospadiac repair and leads to good cosmetic outcome with low risk of complications.  相似文献   
16.
17.
Human tumor–infiltrating lymphocytes (TILs) derived from pleural or ascitic fluid were incubated with recombinant interleukin 2 and transfected with human tumor necrosis factor (TNF) a gene by the lipofection procedure. The resulting TILs secreted significant amounts of TNF in the culture supernatant and exhibited cytotoxicity against established cell lines, such as K562 and Daudi, and autologous tumor cells. The TNF gene–transfected TILs exhibited an augmented killing of autologous tumor cells.  相似文献   
18.
Gross hemorrhage is the most serious complication of anticoagulant therapy. We report the discovery and treatment of a large pseudoaneurysm of the superior gluteal artery in one patient who had been receiving oral anticoagulant therapy. We diagnosed the pseudoaneurysm by contrast-enhanced computed tomography, and embolized the artery with stainless steel coils. The exact cause of the pseudoaneurysm remains unclear, however, minor trauma appears most likely.  相似文献   
19.
An examination was made of neurogenesis in the anteroventral periventricular nucleus (AVPv) of the preoptic area of the rat using bromodeoxyuridine (BrdU), a thymidine analog, and a BrdU-specific antibody. Cells in the AVPv of adult rats were labeled with the antibody when BrdU was injected into pregnant rats once during day 13 to 18 of gestation, but not during day 10 to 12 nor 19 to 20 of gestation nor on postnatal day 1, indicating that neurogenesis of the AVPv occurs during a limited period from day 13 to 18 of gestation. Next, to examine the effects of androgen on neurogenesis, BrdU was injected once on day 15 into pregnant rats that also received injections of testosterone propionate (TP). The number of BrdU-labeled cells in the AVPv was similar in control female and male fetuses and female fetuses from pregnant rats that received daily injections of TP during days 14 to 16, when fetuses were examined on day 17 of gestation. These results suggest that the neurogenesis that was recognized by labeling with BrdU was not affected by the treatment with TP. On day 21 of gestation, BrdU-labeled cells in the AVPv of control male fetuses and female fetuses that received TP during days 14 to 18 were fewer in number than those in female fetuses of the control group, whereas treatments with TP during days 14 to 16 and during days 17 to 18 did not cause any significant decrease in number of BrdU-labeled cells. These findings support the hypothesis that elimination of a population of cells, for example, by cell death as described previously, is enhanced in male fetuses and in female fetuses treated with TP repetitively.  相似文献   
20.
We describe a procedure for “chain-link” combined tissue transfer connecting the vascular pedicle of a deep circumflex iliac flap with that of a forearm flap after wide resection of the mandible. Combination of these flaps facilitated the reconstruction of the defect in both intra- and extraoral soft tissue and the mandibular bone. This method is useful when cervical recipient blood vessels are limited due to the wide resection of the primary tumor and radical neck dissection.  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