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   26934篇
  免费   1464篇
  国内免费   149篇
耳鼻咽喉   278篇
儿科学   559篇
妇产科学   634篇
基础医学   3457篇
口腔科学   1042篇
临床医学   1938篇
内科学   7166篇
皮肤病学   916篇
神经病学   2025篇
特种医学   502篇
外科学   4379篇
综合类   174篇
一般理论   3篇
预防医学   1932篇
眼科学   442篇
药学   1471篇
中国医学   122篇
肿瘤学   1507篇
  2023年   189篇
  2022年   352篇
  2021年   961篇
  2020年   446篇
  2019年   902篇
  2018年   1046篇
  2017年   583篇
  2016年   596篇
  2015年   765篇
  2014年   1121篇
  2013年   1400篇
  2012年   2204篇
  2011年   2253篇
  2010年   1332篇
  2009年   1164篇
  2008年   1828篇
  2007年   1879篇
  2006年   1728篇
  2005年   1537篇
  2004年   1430篇
  2003年   1365篇
  2002年   1254篇
  2001年   179篇
  2000年   157篇
  1999年   188篇
  1998年   197篇
  1997年   150篇
  1996年   148篇
  1995年   126篇
  1994年   100篇
  1993年   84篇
  1992年   83篇
  1991年   69篇
  1990年   64篇
  1989年   45篇
  1988年   46篇
  1987年   38篇
  1986年   25篇
  1985年   40篇
  1984年   38篇
  1983年   40篇
  1982年   47篇
  1981年   45篇
  1980年   45篇
  1979年   18篇
  1978年   24篇
  1977年   26篇
  1975年   24篇
  1974年   23篇
  1973年   18篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
941.

Background

Between 2 and 8 weeks before surgery, most bariatric surgery groups establish strict dietary treatments with a total caloric intake of less than 1,000 kcal/day in order to maximize weight loss during this period of time.

Methods

A prospective randomized clinical trial of all the patients undergoing laparoscopic sleeve gastrectomy (LSG) was performed. Patients were randomly assigned into 3 groups: those patients receiving a preoperative regular diet of 900 kcal/day (group 1), those receiving a preoperative balanced energy high-protein formula (group 2) and those receiving preoperative Immunonutrition (group 3). Preoperative weight loss, postoperative pain, complications and analytical acute phase reactants were investigated.

Results

Sixty patients were included in the study, 20 in each group. Preoperative excess weight loss was 7.7 % in group 1, 12.3 % in group 2 and 15.3 % in group 3 (p?=?0.014). Median postoperative pain was 3.5 in group 1, 3 in group 2 and 2 in group 3 (p?=?0.048). C-reactive protein determined 24 h after surgery was significantly lower in group 3 than in the other groups. AST and ALT values were significantly lower in group 3 than in the other groups, without significant differences between groups 1 and 2.

Conclusions

Preoperative diet with Immunonutrition formulas during 2 weeks achieves a greater preoperative weight loss, lower postoperative pain and lower values of CRP and liver enzymes than high-protein formulas or regular diet, all of them with similar caloric intake.
  相似文献   
942.
943.

Background

In bariatric surgery, there are no guidelines available for intraoperative fluid administration. Goal-directed fluid therapy (GDFT) is a new concept of perioperative fluid management that has been shown to improve the prognosis of patients undergoing abdominal surgery. The aim of our study is to assess the impact of the implementation of a GDFT protocol in morbidly obese patients who underwent laparoscopic sleeve gastrectomy (LSG).

Methods

A before-after intervention study, in morbidly obese patients who underwent LSG, was conducted at the Obesity Unit of the General University Hospital Elche. Data from the GDFT implementation group (January 2014 to December 2015) were prospectively collected and compared with a preimplementation group (January 2012 to December 2013).

Results

Baseline demographic and comorbidity data between the two groups of patients were similar. The length of stay in the hospital was significantly shortened in GDFT group from 4.5 to 3.44 days (p?<?0.001). Intraoperative fluid administration was significantly lower in the GDFT group (1002.4 vs 1687.2 ml in preimplementation group, p?<?0.001). In the postoperative period, there was a statistically significant reduction in postoperative nausea and vomiting (PONV) after GDFT implementation (48 to 14.3 %, p?<?0.001).

Conclusions

Implementation of GDFT protocols can prevent intraoperative fluid overload in patients undergoing bariatric surgery. It could improve outcomes, for example decreasing PONV or even hospital stay.
  相似文献   
944.
New subventricular zone (SVZ)-derived neuroblasts that migrate via the rostral migratory stream are continuously added to the olfactory bulb (OB) of the adult rodent brain. Anosmin-1 (A1) is an extracellular matrix protein that binds to FGF receptor 1 (FGFR1) to exert its biological effects. When mutated as in Kallmann syndrome patients, A1 is associated with severe OB morphogenesis defects leading to anosmia and hypogonadotropic hypogonadism. Here, we show that A1 over-expression in adult mice strongly increases proliferation in the SVZ, mainly with symmetrical divisions, and produces substantial morphological changes in the normal SVZ architecture, where we also report the presence of FGFR1 in almost all SVZ cells. Interestingly, for the first time we show FGFR1 expression in the basal body of primary cilia in neural progenitor cells. Additionally, we have found that A1 over-expression also enhances neuroblast motility, mainly through FGFR1 activity. Together, these changes lead to a selective increase in several GABAergic interneuron populations in different OB layers. These specific alterations in the OB would be sufficient to disrupt the normal processing of sensory information and consequently alter olfactory memory. In summary, this work shows that FGFR1-mediated A1 activity plays a crucial role in the continuous remodelling of the adult OB  相似文献   
945.
946.
In the last decade, chronic kidney disease (CKD), defined as reduced renal function (glomerular filtration rate (GFR) < 60 mL/min per 1.73 m2) and/or evidence of kidney damage (typically manifested as albuminuria) for at least 3 months, has become one of the fastest‐growing public health concerns worldwide. CKD is characterized by reduced clearance and increased serum accumulation of metabolic waste products (uremic retention solutes). At least 152 uremic retention solutes have been reported. This review focuses on indoxyl sulphate (IS), a protein‐bound, tryptophan‐derived metabolite that is generated by intestinal micro‐organisms (microbiota). Animal studies have demonstrated an association between IS accumulation and increased fibrosis, and oxidative stress. This has been mirrored by in vitro studies, many of which report cytotoxic effects in kidney proximal tubular cells following IS exposure. Clinical studies have associated IS accumulation with deleterious effects, such as kidney functional decline and adverse cardiovascular events, although causality has not been conclusively established. The aims of this review are to: (i) establish factors associated with increased serum accumulation of IS; (ii) report effects of IS accumulation in clinical studies; (iii) critique the reported effects of IS in the kidney, when administered both in vivo and in vitro; and (iv) summarize both established and hypothetical therapeutic options for reducing serum IS or antagonizing its reported downstream effects in the kidney.  相似文献   
947.
948.
949.
AIMS: To describe 13 examples of clear cell dermal duct tumour, a neoplasm previously underrecognized in the literature. METHODS AND RESULTS: Thirteen examples of a neoplasm that we have named clear-cell dermal duct tumour were studied histopathologically and immunohistochemically. Histopathologically, all lesions consisted of mostly dermal neoplasms mainly composed of multiple solid aggregations of clear cells involving the dermis. Although the neoplasms were mostly solid, ductal structures were identified in all cases. Immunohistochemically, neoplastic cells were immunoreactive for MNF116 and AE1/AE3 cytokeratins, but not for CAM5.2 or cytokeratin 7. Epithelial membrane antigen, carcinoembryonic antigen and glial cystic disease fibrillary protein 15 decorated the ductal structures, but neoplastic cells were negative. In contrast to some other clear cell neoplasms of the skin, which may be associated with diabetes mellitus, none of our cases of clear cell dermal duct tumour developed in a diabetic patient. CONCLUSIONS: We consider these neoplasms to be clear cell dermal duct tumours for the following reasons: (i) the neoplasms were mostly composed of multiple solid aggregations of epithelial clear cells; (ii) neoplastic aggregations mostly involved the dermis; (iii) in some cases, neoplastic aggregations of conventional poroid cells were intermingled with the aggregations of clear cells; (iv) ductal structures were identified within some neoplastic aggregations; (iv) small areas of necrosis en masse were seen in some neoplastic aggregations; and (v) the stroma of the neoplasm was scant.  相似文献   
950.
Spindle cell and epithelioid cell differentiation occur in both benign and malignant hyperpigmented melanocytic lesions. Reed nevus is characterized by compact, sharply circumscribed junctional cellular nests composed of slender hyperpigmented melanocytes shaped like spindle cells. Deep penetrating nevus is characterized by a diffuse dermal proliferation composed of small nests and fascicles of pale ovoid and epithelioid melanocytes. Cellular blue nevi often have a characteristic hourglass or dumbbell shape, with sharply circumscribed elongated nests and fascicles of pale, densely layered ovoid melanocytes and adjacent melanophages. Epithelioid blue nevus is characterized by large epithelioid melanocytes with abundant cytoplasm and melanin often concentrated to some degree in the cell membrane. Animal-type melanoma is a particularly hyperpigmented variant of melanoma in which large melanophages predominate and there are varying proportions of melamin-rich spindle-shaped and large atypical epithelioid melanocytes. Morphologically, pigmented epithelioid melanocytoma combines characteristics of both animal-type melanoma and pigmented epithelioid nevus. Malignant melanoma may occur in conjunction with a preexistent blue nevus. Malignant blue nevus is now regarded as a malignant melanoma mimicking a blue nevus in structure and pattern. It is therefore of paramount importance to view multiple mitoses within a cellular blue nevus-like proliferation as an alarm signal as they are usually indicators of a malignant melanoma.  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