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   5634篇
  免费   420篇
  国内免费   85篇
耳鼻咽喉   73篇
儿科学   202篇
妇产科学   82篇
基础医学   942篇
口腔科学   81篇
临床医学   549篇
内科学   1181篇
皮肤病学   120篇
神经病学   546篇
特种医学   326篇
外科学   720篇
综合类   54篇
现状与发展   2篇
预防医学   269篇
眼科学   110篇
药学   436篇
中国医学   44篇
肿瘤学   402篇
  2023年   41篇
  2022年   112篇
  2021年   256篇
  2020年   122篇
  2019年   175篇
  2018年   165篇
  2017年   135篇
  2016年   177篇
  2015年   243篇
  2014年   298篇
  2013年   338篇
  2012年   483篇
  2011年   463篇
  2010年   256篇
  2009年   206篇
  2008年   318篇
  2007年   302篇
  2006年   301篇
  2005年   208篇
  2004年   219篇
  2003年   142篇
  2002年   154篇
  2001年   110篇
  2000年   100篇
  1999年   82篇
  1998年   47篇
  1997年   35篇
  1996年   30篇
  1995年   35篇
  1994年   28篇
  1993年   21篇
  1992年   39篇
  1991年   43篇
  1990年   47篇
  1989年   50篇
  1988年   19篇
  1987年   32篇
  1986年   33篇
  1985年   31篇
  1984年   23篇
  1983年   19篇
  1979年   19篇
  1976年   11篇
  1973年   11篇
  1972年   15篇
  1971年   18篇
  1970年   14篇
  1969年   13篇
  1968年   10篇
  1966年   12篇
排序方式: 共有6139条查询结果,搜索用时 51 毫秒
131.
132.
We evaluated p53, KRAS, BRAF and CTNNB1 mutation and p53, WT1, p16 and beta‐catenin expression in 31 ovarian high‐grade serous adenocarcinoma. Twenty‐five (80.6%) tumors contained functional mutations of p53; three frameshift, four nonsense and 19 missense mutations. None of the tumors showed KRAS, BRAF or CTNNB1 mutation. In all 18 tumors with missense mutations, ≥60% of tumor cells were strongly positive for p53 immunostaining whereas all tumors with frameshift or nonsense mutations were completely negative. Missense mutation was correlated with diffuse and strong imunoreaction and frameshift/nonsense mutation was correlated with completely negative immunoreaction (P = 0.000). Tumors with wild‐type p53 revealed a wide range of immunostaining patterns. In 27 (87.1%) and 18 (58.1%) tumors, ≥50% of tumor cells were moderate to strongly positive for WT1 and p16, respectively. A considerable intratumoral heterogeneity for p16 expression was present. None of the tumors demonstrated nuclear beta‐catenin expression. p53 mutations appear to be a powerful molecular marker for ovarian high‐grade serous adenocarcinoma. Using p53 with an appropriate interpretation criteria together with WT1, p16 and beta‐catenin, most of the high‐grade serous adenocarcinoma could be distinguished from other ovarian tumors.  相似文献   
133.
In a developing nervous system, axon‐dendrite formation is instructed by extrinsic cues, and the mechanism whereby a developing neuron interprets these cues using intracellular signaling is particularly important. Studies using dissociated hippocampal neurons have identified many signaling pathways underlying neuronal polarization. Among the components of these pathways, Rap1B is essential for axon specification in hippocampal cultures. However, spatiotemporal regulation of Rap1B activity in polarizing neurons and how it affects neuronal polarization remain unclear. Herein, we investigated spatiotemporal activity‐change of Rap1B and its target molecules in hippocampal neurons. FRET imaging showed that specific activation of Rap1B was observed at the tip of a future axon. To dissect downstream signaling, we used three effector mutants of Rap1B. Expression of Rap1B‐G12V/E37G and G12V/Y40C mutants resulted in supernumerary axons. The targets of Rap1B‐G12V/E37G were RalA and Nore1A, whereas Rap1B‐G12V/Y40C activated PI3‐kinase. RalA was activated in the tip of stage 3 axons, and RalA‐S28N expression reduced the fraction of neurons with supernumerary axons induced by Rap1B‐G12V/E37G. Furthermore, Nore1A depletion reduced the number of cells without axons. These results indicate that specific activation of Rap1B contributes to neuronal polarization via interaction with RalA and Nore1A in addition to PI3‐kinase.  相似文献   
134.
135.
136.

Objective:

To evaluate the diagnostic accuracy of three-dimensional (3D) enhanced T1 high-resolution isotropic volume excitation (eTHRIVE) shoulder MR for variable shoulder pathology such as rotator cuff tear, labral injury and synovial pathology in comparison with two-dimensional enhanced fast spin echo T1 fat saturation (2D T1 FS) sequences MR.

Methods:

This retrospective study included 86 patients who underwent MRI of the shoulder using eTHRIVE technique. Two radiologists evaluated anatomic identification of the supraspinatus, glenoid labrum and acromioclavicular joint (AC joint) on routine MRI sequences (2D T1 FS) and compared them with the reformatted eTHRIVE images. Subjective scoring of the images was performed with a four-point scale that rated the degree of discrimination of the shape of the supraspinatus, glenoid labrum and AC joint. The diagnostic accuracy of eTHRIVE compared with routine MR images was evaluated in terms of rotator cuff pathology, labral pathology and synovial pathology.

Results:

Anatomic identification scores of the supraspinatus tendon and labrum were significantly lower for eTHRIVE than for 2D T1 FS. There were no significant differences between eTHRIVE and 2D T1 FS in anatomic identification of the AC joint. There were no significant differences between eTHRIVE and 2D T1 FS in diagnosing the three disease categories.

Conclusion:

eTHRIVE had comparable diagnostic accuracy to 2D T1 FS imaging in the evaluation of rotator cuff tears, labral injury and synovial pathology, but anatomic identification was inferior to that of 2D T1 FS.

Advances in knowledge:

The accuracy of 3D eTHRIVE imaging is comparable to that of 2D T1 FS for the diagnosis of rotator cuff tears, labral injury and synovial pathology.  相似文献   
137.
ObjectiveTo evaluate the correlation between bone tunnel diameter after anterior cruciate ligament (ACL) reconstruction measured by computed tomography (CT) using multiplanar reconstruction (MPR) and stability or clinical scores.ResultsThe tibial bone tunnels for the anteromedial bundles were significantly widened at T2 compared with T1 (observer 1, 0.578 mm to 0.698 mm, p value of < 0.001; observer 2, 0.581 mm to 0.707 mm, p value of < 0.001). There was no significant correlation between the diameter at T2 and stability or clinical scores and between the interval change ratio ([T2 - T1] / T1) and stability or clinical scores (corrected p values for all were 1.0). Intraobserver agreement for measurements was excellent (> 0.8) for both observers. Interobserver agreement for measurement was excellent (> 0.8) except for the most distal portion of the femoral bone tunnel for anterior medial bundle in immediate postoperative CT, which showed moderate agreement (concordance correlation coefficient = 0.6311).ConclusionNeither the diameter nor its change ratio during interval follow-up is correlated with stability or clinical scores.  相似文献   
138.
ObjectiveWe described the technique of ultrasound (US)-guided percutaneous removal of the foreign bodies (FB) with hydro-dissection in the radiologic department and presented video files of several cases.ResultsThe mean time required for the entire procedure was approximately 20 minutes. There were no significant complications during the US-guided removal or long-term complications after the procedure. All 4 FBs were successfully removed from the soft tissue under US guidance.ConclusionUltrasound-guided percutaneous removal of the FBs with hydro-dissection in the radiology department is a less invasive and safe method over surgical removal in the operating room. Additionally, the use of a guide wire and serial dilator may help minimize soft tissue injury and facilitate the introduction of forceps.  相似文献   
139.
The intrauterine environment during pregnancy is a critical factor in the development of diabetes and obesity in offspring. To determine the effects of maternal exercise during pregnancy on the metabolic health of offspring, 6-week-old C57BL/6 virgin female mice were fed a chow (21%) or high-fat (60%) diet and divided into four subgroups: trained (housed with running wheels for 2 weeks preconception and during gestation), prepregnancy trained (housed with running wheels for 2 weeks preconception), gestation trained (housed with running wheels during gestation), or sedentary (static cages). Male offspring were chow fed, sedentary, and studied at 8, 12, 24, 36, and 52 weeks of age. Offspring from chow-fed dams that trained both before and during gestation had improved glucose tolerance beginning at 8 weeks of age and continuing throughout the 1st year of life, and at 52 weeks of age had significantly lower serum insulin concentrations and percent body fat compared with all other groups. High-fat feeding of sedentary dams resulted in impaired glucose tolerance, increased serum insulin concentrations, and increased percent body fat in offspring. Remarkably, maternal exercise before and during gestation ameliorated the detrimental effect of a maternal high-fat diet on the metabolic profile of offspring. Exercise before and during pregnancy may be a critical component for combating the increasing rates of diabetes and obesity.  相似文献   
140.
A perioperative intravenous lidocaine infusion has been reported to decrease postoperative pain. The goal of this study was to evaluate the effectiveness of intravenous lidocaine in reducing postoperative pain for laparoscopic colectomy patients. Fifty-five patients scheduled for an elective laparoscopic colectomy were randomly assigned to 2 groups. Group L received an intravenous bolus injection of lidocaine 1.5 mg/kg before intubation, followed by 2 mg/kg/h continuous infusion during the operation. Group C received the same dosage of saline at the same time. Postoperative pain was assessed at 2, 4, 8, 12, 24, and 48 hours after surgery by using the visual analog scale (VAS). Fentanyl consumption by patient-controlled plus investigator-controlled rescue administration and the total number of button pushes were measured at 2, 4, 8, 12, 24, and 48 hours after surgery. In addition, C-reactive protein (CRP) levels were checked on the operation day and postoperative days 1, 2, 3, and 5. VAS scores were significantly lower in group L than group C until 24 hours after surgery. Fentanyl consumption was lower in group L than group C until 12 hours after surgery. Moreover, additional fentanyl injections and the total number of button pushes appeared to be lower in group L than group C (P < 0.05). The CRP level tended to be lower in group L than group C, especially on postoperative day1 and 2 and appeared to be statistically significant. The satisfaction score was higher in group L than group C (P = 0.024). Intravenous lidocaine infusion during an operation reduces pain after a laparoscopic colectomy.Key words: Analgesics, Colectomy, Pain, LidocaineBecause of a substantial increase in the incidence of benign and malignant tumors of the colon, the number of laparoscopic colorectal surgeries has increased.1 Laparoscopic colectomy appears to be less painful, involves less bleeding, and has a faster recovery than an open colectomy.2 Further, laparoscopic colorectal surgery has been proven to be beneficial in comparison with robot-assisted laparoscopic colorectal surgery in many aspects.3 However, postoperative pain because of surgical incision is still an issue that requires resolution. Therefore, various clinical applications such as intrathecal morphine, epidural analgesia, patient-controlled analgesia (PCA), and nonsteroidal anti-inflammatory drugs (NSAIDs) are used to control pain after a laparoscopic colectomy.4,5 However, optimal management has not yet been established. A regional block can have technical difficulties and complications. The epidural failure rate has been reported up to 40%, and other drugs, such as opioids or NSAIDs, have side effects or drug allergies.5,6Intravenous lidocaine is inexpensive, easy to inject, and a relatively safe drug.7 A number of studies showed that intravenous lidocaine has analgesic, anti-hyperalgesic, and anti-inflammatory properties, as well as a fast recovery, reducing the hospital stay and the time for bowel function recovery.810 In addition, lidocaine in a nontoxic concentration has been reported to decrease the variant volatile anesthesia requirement in an animal study.10 Therefore, the authors aimed to determine whether a continuous infusion of intravenous lidocaine would have an adequate postoperative analgesic effect for a laparoscopic colectomy. The hypothesis of this study was that an intravenous lidocaine infusion during an operation could decrease postoperative pain.  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