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   14055篇
  免费   790篇
  国内免费   138篇
耳鼻咽喉   285篇
儿科学   251篇
妇产科学   341篇
基础医学   2050篇
口腔科学   411篇
临床医学   1189篇
内科学   2849篇
皮肤病学   255篇
神经病学   1075篇
特种医学   712篇
外科学   1877篇
综合类   174篇
一般理论   1篇
预防医学   769篇
眼科学   431篇
药学   1192篇
中国医学   170篇
肿瘤学   951篇
  2023年   101篇
  2022年   249篇
  2021年   469篇
  2020年   204篇
  2019年   334篇
  2018年   438篇
  2017年   305篇
  2016年   402篇
  2015年   578篇
  2014年   648篇
  2013年   869篇
  2012年   1280篇
  2011年   1206篇
  2010年   686篇
  2009年   583篇
  2008年   802篇
  2007年   746篇
  2006年   717篇
  2005年   619篇
  2004年   556篇
  2003年   460篇
  2002年   408篇
  2001年   372篇
  2000年   321篇
  1999年   240篇
  1998年   116篇
  1997年   79篇
  1996年   67篇
  1995年   71篇
  1994年   58篇
  1993年   58篇
  1992年   121篇
  1991年   91篇
  1990年   95篇
  1989年   99篇
  1988年   85篇
  1987年   79篇
  1986年   57篇
  1985年   53篇
  1984年   31篇
  1983年   29篇
  1982年   22篇
  1981年   12篇
  1980年   16篇
  1979年   14篇
  1978年   17篇
  1977年   18篇
  1976年   14篇
  1975年   17篇
  1974年   17篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Indwelling urethral catheter placement is a common and comparatively safe procedure. Misplacement of a urethral catheter into the upper urinary tract is unusual, and only a few cases have been reported. We describe the case of a 43-year-old man who presented with oliguria and had a history of chemotherapy for known metastatic lung cancer. As he had no history of urological disease, urethral catheterization was expected to be uneventful. The catheter was unable to be pulled back to the bladder neck once the balloon was inflated, and the patient expressed discomfort. Subsequent computed tomography revealed that the tip of the catheter was placed in the middle of the right ureter. Unbeknownst to the physicians before urethral catheterization, the patient had severe lower urinary tract symptoms and urinary bladder dysfunction with hydronephrosis, likely due to chemotherapy. Based on the patient’s symptoms and imaging results, we judged the possibility of severe ureteral injury to be low. The malpositioned catheter was removed uneventfully after complete balloon deflation and then reinserted properly. He was admitted to the medical department but died as a result of an exacerbation of the underlying disease unrelated to the incident. If urethral catheter placement seems abnormal, physicians should aspirate and irrigate to confirm correct positioning before balloon inflation; then, they should carefully pull the inflated balloon near the neck of the bladder while monitoring the patient’s symptoms. Although urethral catheter placement is comparatively safe, physicians must keep in mind that patients who have undergone chemotherapy might be at a risk for this rare complication.  相似文献   
72.
ObjectiveTo examine the effect of a Housing First (HF) intervention and health-related risk factors on incarceration among adults with experiences of homelessness and mental illness.MethodsParticipants (N = 508) were recruited at the Toronto site of the At Home/Chez Soi study. The outcome was incarceration in Ontario from 2009 to 2014. Exposures were intervention group (HF vs. treatment as usual), Axis I mental health diagnoses, emergency department (ED) visit, and history of traumatic brain injury (TBI). Logistic regression was used to examine the association between exposures and incarceration.ResultsOf 508 participants, 220 (43.3%) were incarcerated at least once during the study period. Among those incarcerated, 81.9% were male, 52.7% had been diagnosed with alcohol dependence/abuse, 60.9% had been diagnosed with substance dependence/abuse, 65.1% reported having visited an ED within the last 6 months, and 66.4% had a history of TBI. After adjusting for demographic covariates, substance dependence/abuse (aOR: 2.06; 95% CI: 1.40, 3.03), alcohol dependence/abuse (aOR: 1.52, 95% CI: 1.04, 2.22), ED visit (aOR: 1.54; 95% CI: 1.02, 2.32), and history of TBI (aOR: 2.60; 95% CI: 1.75, 3.85) were associated with incarceration. We found no significant effect of the HF intervention on incarceration outcome (aOR: 1.08; 95% CI: 0.76, 1.55).ConclusionsAmong adults with experiences of homelessness and severe mental illness, those with substance and alcohol dependence/abuse disorders, history of TBI, and recent ED visits were at increased odds of incarceration. Strategies are needed to prevent and reduce incarceration for this population, including treatment of mental illness in the community.Supplementary InformationThe online version of this article (10.17269/s41997-020-00433-z) contains supplementary material, which is available to authorized users.  相似文献   
73.
74.
The authors report a typical case of tenosynovial giant cell tumor of the right middle finger of a 31-year-old man. Histologically, this tumor is characterized by a discrete proliferation of rounded synovial-like cells accompanied by a variable number of multinucleated giant cells, inflammatory cells, and xanthoma cells. Clinicopathologically, this tumor is a benign lesion that nonetheless possesses a capacity for local recurrence. Local excision with a small cuff of normal tissue is the treatment of choice in this tumor.  相似文献   
75.
Hwang Y  Feiss M 《Virology》1999,265(2):196-205
Terminase, the DNA packaging enzyme of bacteriophage lambda, is a heteromultimer composed of gpNu1 (181 aa) and gpA (641 aa) subunits, encoded by the lambda Nu1 and A genes, respectively. Similarity between the deduced amino acid sequences of gpNu1 and gpA and the nucleotide binding site consensus sequence suggests that each terminase subunit has an ATP reactive center. Terminase has been shown to have two distinct ATPase activities. The gpNu1 subunit has a low-affinity ATPase stimulated by nonspecific DNA and gpA has a high-affinity ATPase. In previous work, a mutant terminase, gpNu1 K35A holoterminase, had a mild defect in interactions with DNA, such that twofold increased DNA concentrations were required both for full stimulation of the low-affinity ATPase and for saturation of the cos cleavage reaction. In addition, the gpNu1 K35A terminase exhibited a post-cleavage defect in DNA packaging that accounted for the lethality of the Nu1 K35A mutation [Y. Hwang and M. Feiss (1997) Virology 231, 218-230]. In the work reported here, a mutation in the turn of the putative helix-turn-helix DNA binding domain has been isolated as a suppressor of the gpNu1 K35A change. This suppressor mutation causes the change A14V in gpNu1. A14V reverses the DNA-binding defects of gpNu1 K35A terminase, both for stimulation of the low-affinity ATPase and for saturation of the cos cleavage defect. A14V suppresses the post-cleavage DNA packaging defect caused by the gpNu1 K35A change.  相似文献   
76.
Gabapentin in the acute treatment of refractory bipolar disorder   总被引:4,自引:0,他引:4  
Background: Gabapentin, a new anti-epileptic agent, has been anecdotally reported to be effective in the treatment of mania. We systematically assessed the response rate in bipolar patients being treated adjunctively with gabapentin for manic symptoms, depressive symptoms, or rapid cycling not responsive to standard treatments.
Method: Twenty-eight bipolar patients experiencing manic (n=18), depressive (n=5), or rapid-cycling (n=5) symptoms inadequately responsive to at least one mood stabilizer were treated in an open fashion with adjunctive gabapentin. Illness response was assessed using the Clinical Global Impression Scale modified for bipolar disorder (CGI-BP). A 'positive response' was operationalized as a CGI response of much or very much improved.
Results: Fourteen of the 18 (78%) treated for hypomania or mania had a positive response to a dosage range of 600–3600 mg/day. Patients with hypomania responded fastest, with a positive response achieved in 12.7±7.2 days. Patients with classic mania had a mean time to positive response of 25±12 days, and in patients with mixed mania it was 31.8±20.9 days. All of the five patients treated for depression had a positive response within 21±13.9 days. Only one of five patients with rapid cycling had a positive response. Gabapentin was well tolerated by all patients, with the most common side-effect being sedation.
Conclusions: Gabapentin appears to have acute anti-manic and anti-depressant properties as an adjunctive agent for refractory bipolar illness. Prospective double-blind studies are needed to further delineate its acute efficacy when used as monotherapy and its prophylactic efficacy as monotherapy or in conjuction with other mood stabilizers.  相似文献   
77.
Technetium-99m labeled diethylenetriaminepentaacetic acid (DTPA)-galactosyl human serum albumin (GSA) has been used for hepatocellular functional evaluation. This study proposed new and simple parameters to overcome the limitations of conventional parameters, and they were applied to the clinical staging of chronic liver dysfunction. The study group consisted of 93 patients including 81 with liver dysfunction and 12 control patients. In addition to the two conventional parameters, namely, receptor index (LHL15 = liver count divided by the sum of liver and heart counts at 15 minutes) and clearance index (HH15 = heart count at 15 minutes divided by the heart count at 3 minutes), 6 new parameters for Tc-99m GSA uptake and clearance were generated. The conventional receptor index of LHL15 showed a large variation depending on the size of region of interest (ROI) over the heart. The LHL15 normalized by the ROI size (nLHL15) showed more stable data and a better separation of mild liver dysfunction. A hyperbolic relationship between the LHL15 and HH 15 changed to a linear relationship by using the nLHL15 index. The combination of the liver to heart average count ratio at 15 minutes (LH 15) and T-half (minute) of the heart count also could differentiate each stage well. In conclusion, the use of the ROI-area normalized nLHL is recommended instead of the conventional LHL15. The indices of LH15 and T-half could be alternatively used as practical parameters for clinical staging in liver function.  相似文献   
78.
BACKGROUND: Pancreatic serous cystadenoma, mucinous cystic neoplasms, ductal adenocarcinoma with cystic change, and pseudocysts are a spectrum of pancreatic cystic lesions. Their management strategy and prognosis are extremely diverse. Imaging study, cytology, and analysis of the tumor markers of cyst fluid are not always reliable in differentiation of these disease entities. MATERIALS AND METHODS: Fifteen patients with pancreatic cystic neoplasms (including six mucinous cystadenocarcinomas, two mucinous cystic neoplasms with borderline malignancy, two mucinous cystadenomas, and five serous cystadenomas), 4 patients with pancreatic ductal adenocarcinomas with cystic change, and 10 patients with pseudocysts were studied. Echo-guided or computed tomography-guided biopsies of pancreatic cystic lesions and their normal counterparts were conducted on all patients prior to operation or other management. The specimens were assayed for telomerase activity by using TRAP (telomere repeat amplification protocol). The level of telomerase activity in each specimen was semiquantitated as strong, moderate, weak, and none. The final diagnoses were made from histopathological examination of surgically resected or biopsied specimens. The efficacy of telomerase activity as a tumor marker to predict malignancy of pancreatic cystic lesions was evaluated. RESULTS: Three of the four pancreatic ductal adenocarcinomas with cystic change had strong or moderate telomerase activity; four of the six mucinous cystadenocarcinomas had moderate or weak telomerase activity; one of the two mucinous cystadenomas with borderline malignancy had weak telomerase activity; and none of their normal counterparts had detectable telomerase activity. In contrast, none of the two mucinous cystadenomas, five serous cystadenomas, and 10 pseudocysts had detectable telomerase activity. Based on these results, the sensitivity of telomerase activity for prediction of malignancy or premalignancy of pancreatic cystic lesions was 67%, the specificity was 100%, and the positive and negative predictive values were 1.0 and 0.81, respectively. The overall accuracy was 86%. CONCLUSIONS: The differential expressions of telomerase activity have been detected specifically in malignant and premalignant pancreatic cystic tumors, but not in benign cystic neoplasms or pseudocysts. The implications of these results are that telomerase activation takes part in the malignant transformation of pancreatic cystic neoplasms and that telomerase activity is a useful marker to distinguish malignant pancreatic cystic tumors from benign neoplasms and pseudocysts.  相似文献   
79.
80.
Lee BC  Hwang SH  Chang GY 《Neurology》1999,52(3):646-648
Eight older women from two different continents, all with nonketotic hyperglycemia, presented with hemiballismus-hemichorea (HB-HC) and high signal intensity in the contralateral striatum on T1-weighted MRI scans. Correction of underlying hyperglycemia and supportive care resulted in resolution within days to weeks. This characteristic clinicoradiologic picture suggests a clinical syndrome with benign outcome.  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