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   7353篇
  免费   345篇
  国内免费   56篇
耳鼻咽喉   44篇
儿科学   119篇
妇产科学   86篇
基础医学   1368篇
口腔科学   96篇
临床医学   623篇
内科学   1184篇
皮肤病学   192篇
神经病学   883篇
特种医学   261篇
外科学   977篇
综合类   41篇
一般理论   2篇
预防医学   362篇
眼科学   240篇
药学   638篇
中国医学   10篇
肿瘤学   628篇
  2023年   24篇
  2022年   57篇
  2021年   98篇
  2020年   51篇
  2019年   88篇
  2018年   87篇
  2017年   63篇
  2016年   90篇
  2015年   132篇
  2014年   160篇
  2013年   278篇
  2012年   394篇
  2011年   433篇
  2010年   280篇
  2009年   259篇
  2008年   461篇
  2007年   536篇
  2006年   498篇
  2005年   577篇
  2004年   480篇
  2003年   531篇
  2002年   484篇
  2001年   88篇
  2000年   75篇
  1999年   115篇
  1998年   137篇
  1997年   94篇
  1996年   83篇
  1995年   67篇
  1994年   66篇
  1993年   77篇
  1992年   42篇
  1991年   66篇
  1990年   48篇
  1989年   48篇
  1988年   27篇
  1987年   27篇
  1986年   25篇
  1985年   23篇
  1984年   24篇
  1983年   26篇
  1982年   34篇
  1981年   31篇
  1980年   28篇
  1978年   21篇
  1977年   29篇
  1976年   19篇
  1975年   19篇
  1974年   21篇
  1973年   18篇
排序方式: 共有7754条查询结果,搜索用时 15 毫秒
41.
Depression and level of disability are evaluated in acute and chronic low back pain (LBP) patients. To assess the possibility that some somatic symptoms are confounded with pain, the items of the Beck Depression Inventory arc divided into a cognitive-affective and somatic subscale. The sample consisted of 37 chronic LBP patients. 41 acute LBP patients, and 28 healthy participants. The level of disability was assessed by the Oswestry Low Back Pain Disability Questionnaire. Chronic LBP patients, but not acute LBP patients, have more depressive symptoms than controls. Additionally, chronic LBP patients report more somatic symptoms of depression (e.g.. emo ltional and self disturbance complaints) than cognitive-affective symptoms. Finally, correlation statistics reveal significant relations between the level of disability and depression scores. Whereas chronic patients show a significant correlation between the somatic subscale and level of disability, in acute patients the cognitive-affective subscale is significantly related to the level of disability. The findings suggest careful consideration of whether somatic symptoms of depression are related to pain when using self-report measurements of depression in pain patients. The separation of cognitive-affective and somatic symptoms of depression to evaluate pain problems seems appropriate.  相似文献   
42.
Summary Venezuelan equine encephalitis virus was passaged in KB cell cultures. The virus lost its mouse pathogenicity following subcutaneous inoculation during KB cell passage; the attenuated strain also produced smaller plaques than the pathogenic strain. Both strains grew to the same extent inAedes aegypti (L.) mosquitoes after intrathoracic inoculation. If any reversions to pathogenicity occur during development of the attenuated virus in mosquitoes, then the mutation frequency per duplication per particle must be smaller than 3.5×10–6.  相似文献   
43.
Induction of the interleukin-12 (IL-12) cytokine family comprising IL-12, IL-23, IL-27, and IL-12p40 by intracellular pathogens is required for orchestration of cell-mediated immune responses. Macrophages (MΦ) have been shown to be a source of IL-12 following TLR4-dependent activation by Salmonella (S.). In this study another antigen-presenting cell type, the conventional dendritic cell (cDC), was analyzed and its cytokine responses compared with those of MΦ. We generated bone marrow-derived conventional dendritic cells (BMDC) and macrophages (BMMΦ) by incubating murine bone marrow cells with supernatants containing granulocyte/macrophage colony-stimulating factor (GM-CSF) or macrophage colony-stimulating factor (M-CSF), respectively. Stimulation of BMDC and BMMΦ with S. enterica serovar Enteritidis (SE) or LPS resulted in the release of IL-12 and IL-23 by BMDC but not by BMMΦ. Furthermore, BMDC secreted approx. 20-fold more IL-12p40 and IL-27p28 than BMMΦ. However, BMDC and BMMΦ produced similar levels of IL-10. Using BMDC originating from wild-type (wt), TLR2def and TLR4def mice, we show that in BMDC the induction of IL-12, IL-23, and IL-27p28 by SE is dependent on TLR4, whereas low-level production of p40 is also mediated by pattern recognition receptors (PRR) other than TLR4. Interestingly, LPS- and SE-provoked responses of BMDC were remarkably similar indicating that LPS is the primary danger molecule of SE. Taken together, our results point to cDC rather than MΦ as the major producers of the IL-12 family members during in vitro infection with SE. The mechanisms of recognition of SE, however, appear to be the same for cDC and MΦ  相似文献   
44.
To date, little is known about the duration and effectiveness of immunity as well as possible adverse late effects after an infection with SARS-CoV-2. Thus it is unclear, when and if liver transplantation can be safely offered to patients who suffered from COVID-19. Here, we report on a successful liver transplantation shortly after convalescence from COVID-19 with subsequent partial seroreversion as well as recurrence and prolonged shedding of viral RNA.  相似文献   
45.
46.
Transgenic expression in medaka of the Xiphophorus oncogene xmrk, under a pigment cell specific mitf promoter, induces hyperpigmentation and pigment cell tumors. In this study, we crossed the Hd-rR and HNI inbred strains because complete genome information is readily available for molecular and genetic analysis. We prepared an Hd-rR (p53+/−, p53−/−) and Hd-rR HNI hybrid (p53+/−) fish-based xmrk model system to study the progression of pigment cells from hyperpigmentation to malignant tumors on different genetic backgrounds. In all strains examined, most of the initial hyperpigmentation occurred in the posterior region. On the Hd-rR background, mitf:xmrk-induced tumorigenesis was less frequent in p53+/− fish than in p53−/− fish. The incidence of hyperpigmentation was more frequent in Hd-rR/HNI hybrids than in Hd-rR homozygotes; however, the frequency of malignant tumors was low, which suggested the presence of a tumor suppressor in HNI genetic background fish. The effects on tumorigenesis in xmrk-transgenic immature medaka of a single 1.3 Gy irradiation was assessed by quantifying tumor progression over 4 consecutive months. The results demonstrate that irradiation has a different level of suppressive effect on the frequency of hyperpigmentation in purebred Hd-rR compared with hybrids.  相似文献   
47.
The objective of our clinical studies was to develop an effective combination chemotherapy regimen (CHT) with acceptable side effects, consisting of the two most potent drugs used as single agents in breast cancer. We tested the combination of an anthracycline, epirubicin (A) at 70 mg/m2 i.v. on day 1 or (B) at 120 mg/m2 i.v. on day 1 with an alkylating drug ifosfamide (IFO), (C) at 2.5 g/m2 in an i.v. infusion given over 4 h on days 1–3 or (D) at 5 g/m2 in a 24-h i.v. infusion given on day 1. Courses were repeated every 4 weeks. The combinations were given as first-line therapy as follows: CHT (A, C) in six cases and CHT (B, C) in five cases of advanced breast carcinoma, and CHT (B, D) in seven patients with primary inflammatory breast cancer. Due to side effects (e.g., stomatitis, mental disturbances) and applicability, CHT regimen (B, D) was preferred. Responses (12/18) occurred 1–3 cycles earlier than those previously achieved using the conventional epirubicin/cyclophosphamide CHT. We conclude that 5 g/m2 IFO given i.v. over 24 h with uroprotection (mesna) in a two-drug regimen is an effective dose with tolerable toxicity. Alopecia was seen in all cases. However, according to our experience, myelotoxicity is the dose-limiting factor for both of these drugs.Presented at the Satellite Symposium Ifosfamide in Gynecological Tumors of the 5th European Conference on Clinical Oncology and Cancer Nursing, London, September 3–7, 1989  相似文献   
48.
Room temperature recast Nafion
  • 1 General formula:
  • films, prepared under different humidities in the curing atmosphere, were characterized by small- and wide-angle X-ray scattering (SAXS and WAXS). SAXS reveals that the humidity influences the size of the ionic clusters in these polymer films. It was found that the number and size of ionic clusters increases with increasing relative humidity. WAXS indicates the presence of locally ordered regions of the backbone polymer. These results allow a qualitative understanding of the electrochemical behaviour of Nafion recast films cured at different humidities, as described in the literature.  相似文献   
    49.
    The majority of esophageal perforations is caused by endoscopic procedures, while the spontaneous rupture, also known as Boerhaave's syndrome, is rare. Regardless of the cause the esophageal perforation is an urgent surgical problem. The main diagnostic method is a water-soluble contrast study of the esophagus, probably supplemented by a CT-scan. In case of uncertain diagnosis or localisation eosophagoscopy should be performed. We believe that esophageal perforation should be operated, the factor "time" seems to be important for prognosis. In case of early surgical treatment (within 24 hours) a primary suture is sufficient and safe. Only after a delay in diagnosis with extended mediastinal spillage and necrosis of the esophageal wall the use of autogenous tissue to buttress the esophageal repair may be necessary. Esophagectomy should only be performed for perforated carcinomas. We treated 10 patients in a 4-years-period by primary surgical repair combined with drainage. Nine of them survived, only a 82-years old patient died because of an unresectable perforated esophageal carcinoma.  相似文献   
    50.
    After early operation in 49 patients and delayed operation in 114 patients, all with acute hemorrhagic-necrotizing pancreatitis, 65% of patients developed local or general complications. Local complications were abscesses, peritonitis, bleeding, gastrointestinal fistulae or stenoses, and external pancreatic fistulae. Their cause can be traced to the large wound cavity with the tryptic wound surface as well as residual necrosis. The general postoperative complications were shock, acute renal failure, cardiorespiratory insufficiency, gastrointestinal bleeding, ileus, coagulopathy, and sepsis. These may have resulted from the local complications, or may even have been present before operation. If local septic complications do not respond to conservative treatment, they require reoperation. For gastrointestinal fistulae or stenoses, or for pancreatic fistulae, a wait and see attitude is recommended. Generalized complications call for aggressive intensive medical care.Despite the frequency of postoperative complications, the total mortality rate in our series was 30% in patients with partial pancreatic necrosis operated on early, and in patients who received delayed operations for acute hemorrhagic-necrotizing pancreatitis. The 74% mortality rate in early operations of subtotal and total pancreatic necroses was admittedly high. Operative results in those patients who were under our care from the beginning, however, were more encouraging (mortality rate of 50%) and demonstrate that the correct treatment for severe acute hemorrhagic-necrotizing pancreatitis is surgery.
    Résumé Cent soixante trois malades atteints de pancréatite aigüe nécrotico-hémorragique ont subi une opération précoce (49 cas) ou retardée (114 cas): 65% d'entre eux ont développé des complications locales ou générales. Les complications locales ont été des abcès, des péritonites, des hémorragies, des fistules ou sténoses digestives, des fistules pancréatiques externes. La cause en est la large cavité résiduelle postopératoire avec ses surfaces pancréatiques cruentées et ses nécroses résiduelles. Les complications générales ont été des états de choc, des insuffisances rénales aigües, des défaillances cardio-respiratoires, des hémorragies digestives, des iléus, des troubles de la coagulation et des infections. Elles peuvent être la conséquence des complications locales ou peuvent être apparues avant l'opération. Lorsque les complications infectieuses locales ne répondent pas au traitement conservateur, elles doivent être opérées. Pour les fistules et sténoses digestives, pour les fistules pancréatiques, nous recommandons l'expectative. Les complications générales exigent un traitement médical aggressif.Malgré la fréquence des complications postopératoires, la mortalité globale, dans notre série de patients, a été de 30% pour les pancréatites nécrosantes opérées précocement et pour les pancréatites nécrotico-hémorragiques ayant subi une opération retardée. La mortalité de 74% pour les opérations précoces dans les nécroses pancréatiques subtotales ou totales est trop lourde. Mais les résultats obtenus chez les patients qui ont été traités dans notre service dès le début de la maladie ont été plus encourageants (mortalité 50%): ils montrent que la chirurgie est le traitement adéquat de la pancréatite aigüe nécrotico-hémorragique grave.
      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