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   14576篇
  免费   731篇
  国内免费   119篇
耳鼻咽喉   190篇
儿科学   291篇
妇产科学   187篇
基础医学   2226篇
口腔科学   351篇
临床医学   1317篇
内科学   2773篇
皮肤病学   531篇
神经病学   1151篇
特种医学   632篇
外科学   2062篇
综合类   55篇
一般理论   2篇
预防医学   642篇
眼科学   376篇
药学   1330篇
中国医学   187篇
肿瘤学   1123篇
  2023年   101篇
  2022年   318篇
  2021年   512篇
  2020年   279篇
  2019年   360篇
  2018年   403篇
  2017年   342篇
  2016年   489篇
  2015年   647篇
  2014年   752篇
  2013年   824篇
  2012年   1308篇
  2011年   1184篇
  2010年   729篇
  2009年   631篇
  2008年   837篇
  2007年   861篇
  2006年   740篇
  2005年   671篇
  2004年   555篇
  2003年   448篇
  2002年   418篇
  2001年   310篇
  2000年   294篇
  1999年   219篇
  1998年   72篇
  1997年   61篇
  1996年   39篇
  1995年   55篇
  1994年   28篇
  1993年   21篇
  1992年   84篇
  1991年   69篇
  1990年   83篇
  1989年   69篇
  1988年   64篇
  1987年   48篇
  1986年   50篇
  1985年   45篇
  1984年   30篇
  1983年   33篇
  1981年   24篇
  1980年   19篇
  1979年   37篇
  1978年   44篇
  1977年   25篇
  1976年   20篇
  1975年   30篇
  1974年   27篇
  1973年   20篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Radiation proctitis is a frequent acute complication encountered with pelvic irradiation. This study was aimed at establishing the optimal radiation dose for radiation-induced proctitis in rats. Female Wistar rats were used. The rectal specimens were examined morphologically at 5th and 10th day following 10-30 Gy irradiation in single fraction. With increasing dose, mucosal damage became worse, and there was a prominent reaction after > or =15 Gy. We selected 17.5 Gy as an optimal dose for radiation proctitis and examined specimens at day 1-14 and at week 4, 6, 8, and 12 after 17.5 Gy. The rectal mucosa revealed characteristic histological changes with time. An edema in lamina propria started as early as 1-2 days after irradiation and progressed into acute inflammation. On day 7 and 8, regeneration was observed with or without ulcer. Four weeks later, all regeneration processes have been completed with end result of either fibrosis or normal appearing mucosa. This study showed that the radiation injury of the rectum in rat develops in dose-dependent manner as it has reported in previous studies and suggested that 17.5 Gy in single fraction is the optimum dose to evaluate the protective effect of various medications for radiation proctitis in face of the clinical situation.  相似文献   
32.
To reduce surgical stress, fentanyl is frequently used for neurosurgical procedures in which focal and/or global ischemia may occur. However, the effect of fentanyl on cytokine levels during ischemia/reperfusion is still uncertain. The goal of this study was to evaluate the effect of fentanyl infusion on levels of the proinflammatory cytokines, tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta, during global cerebral ischemia/reperfusion in rats using the intracerebral microdialysis technique. Forty male Sprague-Dawley rats weighing 280-320 g were randomly assigned to each of four groups: group 1 (no fentanyl infusion and only ischemia/reperfusion); group 2 (1.5 ng/ml of fentanyl infusion during ischemia/reperfusion) and group 3 (3 ng/ml of fentanyl infusion during ischemia/reperfusion) (n=5 in each group). The rats were anesthetized with an intraperitoneal injection of pentobarbital (50 mg/kg). They were then intubated and ventilated with room air using an animal ventilator. A CMA-12 probe was inserted into the left hippocampal CA-1 region according to the guidelines. Artificial cerebrospinal fluid was run from the inserted microdialysis probe and infused with or without fentanyl at 3 microl/min using a microinjection syringe pump during ischemia/reperfusion. Ischemia was induced by clamping the carotid arteries. Hemorrhagic hypotension was induced for 17 min via the femoral artery, and reperfusion was accomplished by unclamping the sling and reinfusing the blood via the femoral artery. After 2 h of stabilization, the microdialysate was collected 10 times every 17 min, just before ischemia (control), after ischemia (I) and after reperfusion (R1-R8), and stored at -80 degrees C until analysis using high-performance liquid chromatography During global ischemia/reperfusion, TNF-alpha and IL-1beta significantly increased at reperfusion (R5) compared with the control value (p < 0.05). However, in both cases of fentanyl infusion, TNF-alpha and IL-1beta showed no increase compared with the control value. Fentanyl inhibited an increase of the proinflammatory cytokines, TNF-alpha and IL-1beta levels, during global cerebral ischemia/reperfusion in rats.  相似文献   
33.
34.
In most cases, while schwannoma is sporadically manifested as a single benign neoplasm, the presence of multiple schwannomas in one patient is usually indicative of neurofibromatosis 2. However, several recent reports have suggested that schwannomatosis itself may also be a distinct clinical entity. This study examines an extremely rare case of probable schwannomatosis associated with intracranial, intraspinal and peripheral involvements. A 63-year-old woman presented with a seven-year history of palpable lumps on both sides of the supraclavicular area and hearing impairment in both ears. On physical examination, no skin manifestations were evident. Facial sensory change, deafness in the left ear and decreased gag reflex were revealed by neurological examination. Magnetic resonance imaging revealed multiple lesions of the trigeminal nerves, acoustic nerves, lower cranial nerves, spinal accessory nerve, brachial plexuses, and spinal nerves. Pathological examination of tumors from the bilateral brachial plexuses, the spinal nerve in the T8 spinal position and the neck mass revealed benign schwannomas. Following is this patient case report of multiple schwannomas presenting with no skin manifestations of neurofibromatosis.  相似文献   
35.
S K Oh  D L Very  J Walker  S Raam  S T Ju 《Cancer research》1987,47(19):5120-5126
In spite of the numerous reports indicating the presence of humoral immunosuppressive factors in cancer patients, only a few of these factors have been biochemically identified. Furthermore, their role as effective immunosuppressors in vivo remains to be established. Our laboratory has attempted to isolate and identify the major immunosuppressive factor in the malignant effusions derived from ovarian and lung cancer patients. We have previously demonstrated that the Mr 52,000 immunosuppressive factor isolated from the ascites fluid of an ovarian cancer patient inhibited T-dependent immune responses in vivo and in vitro including the inhibition of E-rosetting. Thus, this immunosuppressive factor was named "suppressive E-receptor" (SER). Our current study demonstrates that this SER factor purified from malignant effusions derived from ovarian, lung, or head and neck cancer patients had a common component which dissociated equally into Mr 38,000-42,000 and 17,000-19,000 moieties on sodium dodecyl sulfate-polyacrylamide gel electrophoresis under vigorous reducing conditions. Electroelution of these two components followed by a limited amino acid sequence determination revealed these two components to have N-terminal amino acid sequences identical to the beta and alpha 2 subunits of normal adult haptoglobin. Immunoelectrophoresis of SER using a polyclonal antiserum to neonatal cord blood demonstrated that SER, unlike normal haptoglobin, has slower electrophoretic mobility than the normal adult haptoglobin. Western blotting analysis of SER separated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis under denaturing conditions failed to recognize a monoclonal antibody directed specifically to SER. However, this monoclonal antibody exclusively reacted with the SER separated by an analytical polyacrylamide gel electrophoresis gel under nondenaturing conditions while normal adult haptoglobins or purified but denatured haptoglobin obtained from the same malignant fluid as SER all failed to react with this antibody. Thus, SER appears to bear an additional epitope(s) that is absent in normal adult haptoglobin. Since the SER as well as the neonatal haptoglobin have at least 100 to 1000-fold more potent immunosuppressive activity than the normal adult haptoglobin, this additional epitope(s) present in SER may be responsible for the potent immunosuppressive property of SER.  相似文献   
36.
37.
Goh  S. S. N.  Shelat  V. G.  Lee  B. G. W.  Chen  R. Y.  Oh  S. L.  Chia  C. L. K. 《Hernia》2021,25(5):1223-1229
Hernia - As patients with recurrent inguinal hernia (RIH) are at a higher risk of perioperative complications, international guidelines have been developed to mitigate these risks by recommending...  相似文献   
38.
BackgroundUreaplasma parvum (UP) is commonly isolated in the genitor-urinary tract and may cause various clinical features, including microscopic hematuria (MH). Some UP serovars are more commonly related with specific urogenital disease, but the evidences have been conflicting. This study primarily aimed to research the possible associations between specific UP serotypes and genito-urinary pathogenicity in female patients showing MH with/without chronic micturition urethral pain (CMP).MethodsThis study retrospectively reviewed 276 female patients having MH with/without CMP, who visited health screening center or female infertility clinic. All patients underwent multiplex polymerase chain reaction (PCR) tests with vaginal and urine samples to evaluate the infection rate and serotypes of UP. The antimicrobial susceptibility of UP and the predictors of CMP among UP infected patients were also analyzed. All patients were followed up at least for 6-months.ResultsForty-nine patients (17.8%) showed urinary UP infection. Urinary UP serotyping showed the prevalence of seorvar-1, -3, -6 and -14 were 24.5%, 30.6%, 18.4% and 26.5%, respectively. 79.6% of the urinary UP positive patients accompanied vaginal UP infection. 22 patients of the cohort (8.0%) had CMP whereas serovars-3 and -14 accompanied CMP in 54.5% and 41.0% cases, respectively. No serovars-6 infection case had CMP. 26.4% of the cohort were infertile whereas 10.9% of these infertile patients were positive for urinary tract infection with UP serotype-3 or -14. Doxycycline, josamycin and pristinamycin were the most active antibiotics with the lowest rate of resistance (0.0%) for treating UP. At 1-month post-initial treatment with doxycycline, all UP serotypes were eradicated and no patient complained of urethral discomfort. However, simultaneous urinary and vaginal reinfection of serovar-3 (5 cases) and serovar-5 (1 case) were confirmed at 3-months post-initial doxycycline therapy. The logistic regression analyses revealed that serovars-3 [hazard ratio (HR) 1.354, P value 0.018] and -14 (HR 1.103, P value 0.046) were significantly associated with CMP in female patients having MH.ConclusionsUP serovars-3 and -14 infections could be associated with CMP in female patients having MH. Doxycycline, josamycin and pristinamycin were effective for treating UP. Serovar-3 showed higher reinfection rate than other serotypes after antibiotics treatment.  相似文献   
39.
ObjectiveTo assess the implementation of the Regional framework for action on implementation of the End TB Strategy in the Western Pacific, 2016–2020 in countries and areas in the World Health Organization Western Pacific Region.MethodsWe used a mixed methods approach to assess the framework’s measurable and perceived impact. We conducted an analysis of national tuberculosis strategic plans, a cross-sectional survey of senior staff of tuberculosis programmes, key informant interviews and some country case studies.FindingsOf the 37 countries and areas of the Western Pacific Region, 14 had a national tuberculosis strategic plan, including all countries and areas with a high incidence of tuberculosis. Most senior tuberculosis programme staff who responded to the survey (16/23) found the regional framework useful when developing their national targets and grant applications. Programmatic challenges identified included financing, human resources, public–private mix, active case finding, and paediatric and drug-resistant tuberculosis. Most of the 17 key informants thought that the regional framework’s categorization of actions (for all settings, for specific settings and for pre-elimination settings) was useful, but that the added value of the regional framework over other relevant documents was not obvious because of overlap in content.ConclusionThe regional framework influenced national level tuberculosis control planning and implementation in a positive way. A future regional framework should provide a longer-term strategic horizon and specifically address emerging trends and persistent problems faced by countries or areas of the region.  相似文献   
40.
The aim of this study was to survey the present status and patterns of reirradiation (Re-RT) practice using external beam radiotherapy in Japan. We distributed an e-mail questionnaire to the Japanese Society for Radiation Oncology partner institutions, which consisted of part 1 (number of Re-RT cases in 2008–2012 and 2013–2018) and part 2 (indications and treatment planning for Re-RT and eight case scenarios). Of the 85 institutions that replied to part 1, 75 (88%) performed Re-RTs. However, 59 of these 75 institutions (79%) reported difficulty in obtaining Re-RT case information from their databases. The responses from 37 institutions included the number of Re-RT cases, which totaled 508 in the period from 2009 to 2013 (institution median 3; 0–235), and an increase to 762 cases in the period from 2014 to 2018 (12.5; 0–295). A total of 47 physicians responded to part 2 of the survey. Important indications for Re-RT that were considered were age, performance status, life expectancy, absence of distant metastases and time interval since previous radiotherapy. In addition to clinical decision-making factors, previous total radiation dose, volume of irradiated tissue and the biologically equivalent dose were considered during Re-RT planning. From the eight site-specific scenarios presented to the respondents, >60% of radiation oncologists agreed to perform Re-RT. Re-RT cases have increased in number, and interest in Re-RT among radiation oncologists has increased recently due to advances in technology. However, several problems exist that emphasize the need for consensus building and the establishment of guidelines for practice and prospective evaluation.  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