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   86321篇
  免费   8315篇
  国内免费   6146篇
耳鼻咽喉   742篇
儿科学   1219篇
妇产科学   1045篇
基础医学   9539篇
口腔科学   1332篇
临床医学   11224篇
内科学   12844篇
皮肤病学   786篇
神经病学   4586篇
特种医学   2821篇
外国民族医学   27篇
外科学   8979篇
综合类   16082篇
现状与发展   17篇
一般理论   11篇
预防医学   6103篇
眼科学   2275篇
药学   9013篇
  85篇
中国医学   5367篇
肿瘤学   6685篇
  2024年   342篇
  2023年   1431篇
  2022年   3621篇
  2021年   4576篇
  2020年   3531篇
  2019年   3002篇
  2018年   3017篇
  2017年   2767篇
  2016年   2536篇
  2015年   3869篇
  2014年   4901篇
  2013年   4569篇
  2012年   6448篇
  2011年   7106篇
  2010年   4779篇
  2009年   3983篇
  2008年   4907篇
  2007年   4764篇
  2006年   4414篇
  2005年   4146篇
  2004年   2992篇
  2003年   2908篇
  2002年   2459篇
  2001年   2092篇
  2000年   1909篇
  1999年   1881篇
  1998年   1033篇
  1997年   1155篇
  1996年   811篇
  1995年   754篇
  1994年   626篇
  1993年   446篇
  1992年   502篇
  1991年   432篇
  1990年   361篇
  1989年   327篇
  1988年   286篇
  1987年   248篇
  1986年   207篇
  1985年   157篇
  1984年   80篇
  1983年   86篇
  1982年   53篇
  1981年   58篇
  1980年   32篇
  1979年   46篇
  1978年   20篇
  1977年   17篇
  1974年   18篇
  1973年   16篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
141.
目的:应用微乳液反应法制备磺胺嘧啶银均匀微晶,均匀制得的微晶的粒径大小约为2~4um,均匀微晶的结晶性好,纯度高。用均匀设计方法优化条件,制备的均匀的微晶平均粒径大小为2.09um,实验结果达到预测结果要求。结论:用微乳液反应法能获得磺胺嘧啶银均匀微晶。  相似文献   
142.
目的:为临床应用混合抗体进行放射免疫治疗提供实验依据。方法:在裸鼠荷人大肠癌Lovo移植瘤生长至1cm时,瘤内分别或同时注射~(131)I标记的抗CL_3单克隆抗体(~(131)I-CL_3)和~(131)I标记抗FERR单克隆抗体T_9(~(131)I-T_9),治疗后行SPECT显像观察标记抗体在肿瘤内的浓聚,并进行疗效观察。结果:我们发现两种抗体混合治疗组疗效明显好于单独治疗组,抗体在肿瘤内的浓聚也大于单独应用。结论:多种抗体混合应用瘤内注射放射免疫治疗可增加标记抗体在肿瘤内的浓聚,并能提高放射免疫治疗的疗效。  相似文献   
143.
乙肝基因疫苗系列质粒的构建及其在真核细胞中的表达   总被引:3,自引:0,他引:3  
目的 构建一系列乙肝病毒表面抗原大、中、小蛋白的真核细胞表达质粒,并研究其在真核细胞中的表达情况。方法 采用常规PCR法扩增S、前S2-S、前S1-前S2-S片断,利用重叠PCR法扩增出前S1-S片断后,分别插入Rc/CMV及pSG5UTPL/Flag载体质粒中,并在其ATG起始密码前加入KOZAK序列后转染SP2/0细胞,Western-Blot杂交检测所表达蛋白,并用核酸自动分析仪分析所插入片断的核酸序列。结果 插入片断的核苷酸序列与相应的大、中、小蛋白和前S1-S蛋白的编码基因一致,Western-Blot杂交检测出了相应的目的蛋白。结论 获得了8个能高效表达乙肝病毒表面抗原大、中、小蛋白和前S1-S蛋白的真核细胞表达质粒。  相似文献   
144.
145.
Tang  Xin  Chen  Lixin  Chen  Wenwen  Li  Peiyun  Zhang  Ling  Fu  Ping 《International urology and nephrology》2021,53(9):1911-1921
Purpose

Intradialytic hypotension (IDH) is a serious complication in dialysis patients. Diuretics might reduce the incidence of IDH by decreasing ultrafiltration. However, the effect of diuretics on IDH in maintenance dialysis patients is still unclear.

Methods

We searched Medline, Embase, the Cochrane Library, China National Knowledge Infrastructure and clinical trials registries from 1945 to May 2019. Randomized controlled trials (RCTs) or observational studies about IDH in maintenance dialysis with diuretics were included.

Results

Seven studies including 28,226 patients were included, of which 4 were RCTs involving mineralocorticoid receptor antagonists (MRAs) and 3 were observational studies involving loop diuretics. There was a trend that a lower incidence rate of IDH in maintenance dialysis patients who used loop diuretics than control, although the result was not statistically significant (OR 0.65, 95% CI 0.34–1.22, P?=?0.18). Similarly, lower incidence rate of all-cause mortality (OR 0.92, 95% CI 0.87–0.99; P?=?0.02) and cardiovascular (CV) mortality (OR 0.86, 95% CI 0.75–0.99, P?=?0.03) in dialysis patients who used loop diuretics than control. On the contrary, there were no significant difference in the incidence of IDH (OR 1.35, 95% CI 0.78–2.34, P?=?0.29) and all-cause mortality (OR 0.73, 95% CI 0.26–2.01; P?=?0.54) and CV mortality (OR 0.57, 95% CI 0.14–2.25; P?=?0.42) in maintenance dialysis patients who used MRAs compared with control.

Conclusion

Loop diuretics, but not MRAs, might have a potential benefit to reduce the incidence rate of IDH, all-cause mortality and CV mortality. More high-quality studies are needed to strengthen the arguments.

  相似文献   
146.
Haibin  Wei  Lin  Qian  Junxiu  Wu  Heng  Wang  Qi  Zhang  Yanpeng  Wang  Dahong  Zhang 《Lasers in medical science》2021,36(6):1191-1200

The benefit of transurethral laser prostatectomy over open simple prostatectomy (OSP) is controversial in aged symptomatic benign prostatic hyperplasia (BPH) patients with large volume prostates, and the aim of this study is to compare the safety and efficiency of these two methods. Meta-analysis was applied using the Review Manager V5.3 software and the retrieved randomized controlled clinical trials (RCTs) comparing transurethral laser prostatectomy with OSP were analyzed for the treatment of large volume prostates from 2000 to 2019 in PubMed, Web of Science, Cochrane, and EMBASE datasets. Five RCTs assessing transurethral laser prostatectomy versus OSP were considered suitable for this meta-analysis, which included a total of 448 patients, with 232 patients undergoing laser and 216 patients undergoing OSP. Compared with OSP, although transurethral laser prostatectomy required a longer operative time (weighted mean difference (WMD) 27.49 mins; 95% confidence interval (CI) 16.54–38.44; P?<?0.00001) and obtained a less resected prostate weight (WMD ??11.72 g; 95% CI ??21.75 to ??1.70; P?=?0.02), patients undergoing laser prostatectomy benefited from significantly less hemoglobin decline (??0.97 g/dL; 95% CI ??1.31 to ??0.64; P?<?0.00001), shorter time of catheterization (WMD ??3.67 days; 95% CI ??5.60 to ??1.75; P?=?0.0002), shorter length of hospital stay (WMD ??4.75 days; 95% CI ??6.57 to ??2.93; P?<?0.00001), and less blood transfusion (odds ratio 0.10; 95% CI 0.03 to 0.35; P?=?0.0003). During postoperative follow-up, no significant difference was observed between the two groups in IPSS, QoL, Qmax, and PVR. Both transurethral laser prostatectomy and OSP are safe and effective for large prostates that require prostate resection. Taking into account of less blood loss, shorter catheterization time and hospital stay, and less blood transfusion, transurethral laser prostatectomy may be a better treatment for patients with large prostates.

  相似文献   
147.
Germplasm cryopreservation and expansion of gonocytes/prospermatogonia or spermatogonial stem cells (SSCs) are important; however, it's difficult in cattle. Since inhibitors of Mek1/2 and Gsk3β (2i) can enhance pluripotency maintenance, effects of 2i-based medium on the cultivation of bovine prospermatogonia from the cryopreserved tissues were examined. The testicular tissues of newborn bulls were well cryopreserved. High mRNA levels of prospermatogonium/SSC markers (PLZF, GFRα-1) and pluripotency markers (Oct4/Pouf5, Sox2, Nanog) were detected and the PLZF+/GFRα-1+ prospermatogonia were consistently identified immunohistochemically in the seminiferous cords. Using differential plating and Percoll-based centrifugation, 41.59% prospermatogonia were enriched and they proliferated robustly in 2i medium. The 2i medium boosted mRNA abundances of Pouf5, Sox2, Nanog, GFRα-1, PLZF, anti-apoptosis gene Bcl2, LIF receptor gene LIFR and enhanced PLZF protein expression, but suppressed mRNA expressions of spermatogonial differentiation marker c-kit and pro-apoptotic gene Bax, in the cultured prospermatogonia. It also alleviated H2O2-induced apoptosis of the enriched cells and decreased histone H3 lysine (K9) trimethylation (H3K9me3) and its methylase Suv39h1/2 mRNA level in the cultured seminiferous cords. Overall, 2i medium improves the cultivation of bovine prospermatogonia isolated from the cryopreserved testes, by inhibiting Suv39h1/2-mediated H3K9me3 through Mek1/2 and Gsk3β signalling, evidencing successful cryopreservation and expansion of bovine germplasm.  相似文献   
148.
149.
Xu  Yangyang  He  Qi  Wang  Mengqi  Gao  Yuan  Liu  Xiaowei  Li  Denghui  Xiong  Botao  Wang  Wei 《Neurosurgical review》2021,44(1):115-127
Neurosurgical Review - Magnetic resonance imaging-guided focused ultrasound (MRgFUS) neurosurgery is a new option for medication-resistant Parkinson’s disease (PD), but its safety and...  相似文献   
150.
Screening for aorto-iliac stenosis is important in kidney transplant candidates as its presence affects pre-transplantation decisions regarding side of implantation and the need for an additional vascular procedure. Reliable imaging techniques to identify this condition require contrast fluid, which can be harmful in these patients. To guide patient selection for these imaging techniques, we aimed to develop a prediction model for the presence of aorto-iliac stenosis. Patients with contrast-enhanced imaging available in the pre-transplant screening between January 1st, 2000 and December 31st, 2018 were included. A prediction model was developed using multivariable logistic regression analysis and internally validated using bootstrap resampling. Model performance was assessed with the concordance index and calibration slope. Three hundred and seventy-three patients were included, 90 patients (24.1%) had imaging-proven aorto-iliac stenosis. Our final model included age, smoking, peripheral arterial disease, coronary artery disease, a previous transplant, intermittent claudication and the presence of a femoral artery murmur. The model yielded excellent discrimination (optimism-corrected concordance index: 0.83) and calibration (optimism-corrected calibration slope: 0.91). In conclusion, this prediction model can guide the development of standardized protocols to decide which patients should receive vascular screening to identify aorto-iliac stenosis. External validation is needed before this model can be implemented in patient care.  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