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   91031篇
  免费   7831篇
  国内免费   1139篇
耳鼻咽喉   1066篇
儿科学   2247篇
妇产科学   1713篇
基础医学   12360篇
口腔科学   2149篇
临床医学   9767篇
内科学   17439篇
皮肤病学   1435篇
神经病学   8850篇
特种医学   3559篇
外国民族医学   13篇
外科学   13101篇
综合类   3315篇
一般理论   51篇
预防医学   7623篇
眼科学   2051篇
药学   6824篇
  3篇
中国医学   465篇
肿瘤学   5970篇
  2022年   559篇
  2021年   1314篇
  2020年   727篇
  2019年   1218篇
  2018年   1624篇
  2017年   1351篇
  2016年   1332篇
  2015年   1586篇
  2014年   2124篇
  2013年   3044篇
  2012年   4251篇
  2011年   4437篇
  2010年   2545篇
  2009年   2250篇
  2008年   3968篇
  2007年   4408篇
  2006年   4113篇
  2005年   3779篇
  2004年   3539篇
  2003年   3274篇
  2002年   3144篇
  2001年   4012篇
  2000年   3905篇
  1999年   3330篇
  1998年   1324篇
  1997年   1059篇
  1996年   882篇
  1995年   832篇
  1994年   713篇
  1993年   649篇
  1992年   2279篇
  1991年   2164篇
  1990年   2034篇
  1989年   2056篇
  1988年   1779篇
  1987年   1863篇
  1986年   1731篇
  1985年   1665篇
  1984年   1197篇
  1983年   996篇
  1982年   603篇
  1981年   542篇
  1980年   519篇
  1979年   965篇
  1978年   652篇
  1977年   562篇
  1976年   565篇
  1974年   644篇
  1973年   579篇
  1972年   506篇
排序方式: 共有10000条查询结果,搜索用时 14 毫秒
991.

Objective

To study the efficacy of uterine electrical stimulation (ES) with various parameters in delaying delivery in term- and preterm-laboring animals.

Study design

Catheters and electrodes, as well as ES electrodes, were sutured onto the uterine horn in day-15 pregnant rats. ES with various durations/frequencies (five sets of parameters) was tested from gestation day 21 to determine its effects on uterine contractility. The best set of ES parameters was applied in term (day 21) and preterm (day 18—labor induced) animals to determine the effects of ES on delivery.

Results

(1) Significant reduction in uterine contractions (0.54 ± 0.11 vs. 0.86 ± 0.08 contractions per minute, P < 0.001) was noted with ES of only one of the five sets of parameters (set #5 with pulse train of 10 s on and 10 s off, 28 ms pulse width, frequency of 30 Hz and amplitude of 4 mA); (2) ES with parameter set 5 delayed delivery by 12.5 h (P = 0.01) and reduced area under the curve of intrauterine pressure in mmHg s (311 ± 147.21 vs. 848.75 ± 350.38, P < 0.05) and AUC-electromyographic activity is area under rectified (i.e. absolute value) uterine EMG trace in mV s (145.25 ± 93.1 vs. 410 ± 182.46, P < 0.05) in the term rats; and (3) similar effects were noted with ES in preterm rats with a delay in delivery by 28 h (P < 0.001), and a decrease in IUP–AUC (intrauterine pressure–area under curve) (101.5 ± 55.45 vs. 551 ± 269.06, P = 0.017) and EMG–AUC (64.25 ± 43.63 vs. 172.5 ± 62.91, P = 0.03).

Conclusion

ES of the uterus with appropriate parameters inhibits uterine contractions and delays delivery in both term and preterm rats.  相似文献   
992.
Growth-restricted fetuses are at higher risk for poor perinatal and long-term outcome than those who are appropriately grown. Multiple antenatal testing modalities can help document the sequence of fetal deterioration. The full extent of this compromise is best identified by a combination of fetal biometry, biophysical profile scoring, and arterial and venous Doppler. In the preterm growth-restricted fetus, timing of delivery is critically determined by the balance of fetal versus neonatal risks. In the near-term fetus, accurate diagnosis continues to be a challenge as unrecognized growth restriction contributes to a significant proportion of unexplained stillbirths. In this review, we present an integrated diagnostic and surveillance approach that accounts for these factors.  相似文献   
993.
Fetal growth restriction   总被引:1,自引:0,他引:1  
Normal fetal growth is determined by the genetically predetermined growth potential and further modulated by maternal, fetal, placental, and external factors. Fetal growth restriction (FGR) is a failure to reach this potential and is clinically suspected if sonographic estimates of fetal weight, size, or symmetry are abnormal. Integration of fetal anatomy assessment, amniotic fluid dynamics, uterine, umbilical, and fetal middle cerebral artery Doppler is the most effective approach to differentiate potentially manageable placenta-based FGR from aneuploidy, nonaneuploid syndromes, and viral infection. Although placental dysfunction results in a multisystem fetal syndrome with impacts on short- and long-term outcome, only cardiovascular and behavioral responses are helpful to guide surveillance and intervention. Early-onset FGR before 34 weeks gestation is readily recognized but challenging to manage as questions about optimal delivery timing remain unanswered. In contrast, near-term FGR provides less of a management challenge but is often missed as clinical findings are more subtle. Once placenta-based FGR is diagnosed, integrating multivessel Doppler and biophysical profile score provides information on longitudinal progression of placental dysfunction and degree of fetal acidemia, respectively. Choosing appropriate monitoring intervals based on anticipated disease acceleration and intervention when fetal risks exceed neonatal risks are the prevailing current management approaches.  相似文献   
994.
OBJECTIVE: To examine the degree to which neonatal illness severity, postneonatal health problems, child characteristics, parenting quality as measured by the HOME Inventory, and maternal characteristics are related to the development of wheezing in prematurely born children over the first 27 months after term. DESIGN: Longitudinal predictive study. SETTING: Infants were recruited from two neonatal intensive care units, one in southeast and one in Midwest. PARTICIPANTS: One hundred thirteen preterm infants who weighed less than 1,500 g or required mechanical ventilation and their mothers. MAIN OUTCOME MEASURES: The presence of wheezing was obtained from maternal report at 2, 6, 9, 13, 18, 22, and 27 months. Wheezing was considered to be medically significant if the child was using bronchodilators or pulmonary antiinflammatory medications. RESULTS: Sixty-eight percent of the children had wheezing at least one or more ages; 47% of the children were also taking bronchodilators or pulmonary antiinflammatory medications and thus had medically significant wheezing. CONCLUSION: Postneonatal health problems and the social environment appear to be more important in developing wheezing in prematurely born children than neonatal medical complications.  相似文献   
995.
Developmental Origins Theory has received little coverage in the nursing literature, even though it has received much attention in other sciences. The theory proposes that prenatal stress provokes adaptive changes in endocrine and metabolic processes that become permanently programmed and impact later adult health. This paper reviews the theory and describes the primary neuroendocrine mechanism of hypothalamic-pituitary-adrenal axis function. Supporting research evidence in preterm infant and adult samples is presented. Through knowledge of the theory and the long-term sequelae for preterm infants, nurses will have a different theoretical perspective and growing evidence to consider in their care for pregnant women and infants.  相似文献   
996.
997.
OBJECTIVE: Evaluate the effects of skin infiltration with ropivacaine 0,75% on postoperative pain after caesarean section in the first 24h. PATIENTS AND METHODS: A prospective randomized double blind study was realized during three months in Auxerre Hospital. All ASA 1-2 patients presenting for elective caesarean section under spinal anesthesia were enrolled in the study. Drug addicts and patients with chronic pain were excluded from the study. The patients were randomly divided into two groups to receive skin infiltration 20 ml of ropivacaine 0,75% (Gr R) or skin infiltration of 20 ml of 0,9% saline solution. All patients received systematically propacetamol 1g per six hours and ketoprofen 50mg per six hours. Intravenous morphine titration was delivered to patients with a simple numerical scale greater or equal to three (SNS> or =3). Postoperative pain (SNS), morphine consumption and adverse reactions were compared. RESULTS: From July to September 2005, 42 patients were enrolled in the study. The SNS was lower in the Gr R. Total morphine consumption was reduced in the Gr R. The incidence of the adverse effects were higher in the Gr P. One case of parietal haematoma was detected in the Gr P, the evolution of which was favorable. DISCUSSION AND CONCLUSION: Skin infiltration of ropivacaine 0,75% is a simple technique able to reduce postoperative pain score and morphine consumption after caesarean section.  相似文献   
998.
OBJECTIVE: Cyclic platinum-based intraperitoneal chemotherapy has proven to be effective after optimal surgical cytoreduction in ovarian carcinoma. Hyperthermia is directly cytotoxic and enhances chemotherapy tumoricidal effects. This study was designed to determine the maximum tolerated dose (MTD) of carboplatin used intraoperatively as intraperitoneal hyperthermic chemotherapy (IPHC), the effect on postoperative systemic chemotherapy administration, and the potential for repeat IPHC at second look surgery. METHODS: Using the ThermoChem HT System, escalating doses of carboplatin (400, 600, 800, 1000, and 1200 mg/m(2)) were administered intraoperatively as IPHC with a perfusion time of 90 min. A subgroup of eight patients that received initial IPHC and subsequent systemic chemotherapy underwent second look reassessment surgery with IPHC. RESULTS: The first 4 dose levels were well tolerated without dose-defining toxicity. The initial two patients treated at 1200 mg/m(2) developed grade 4 myelosuppression thus defining the MTD at 1000 mg/m(2). Newly diagnosed ovarian cancer patients receiving the initial IPHC at the MTD defined above completed standard systemic chemotherapy with six courses of systemic chemotherapy. Eight patients having initial IPHC and systemic chemotherapy subsequently had repeat IPHC performed at second look laparotomy without grade 3 or 4 toxicities. Four patients were found to have extensive adhesions at the time of second look reassessment surgery yet completed IPHC. CONCLUSIONS: The MTD for intraperitoneal carboplatin administered as IPHC was established at 1000 mg/m(2). IPHC at the initial cytoreductive procedure did not preclude subsequent systemic chemotherapy. In addition, repetitive IPHC was feasible at second look reassessment surgery.  相似文献   
999.
Glycol ethers (GE) belong to two main series: series E, which include ethylene glycol ethers (EGE) and series P which include propylene glycol ethers (PGE). GE are widely used as solvents in a large number of industrial, household and cosmetic applications. EGE can be found in water paints, varnishes, inks, household products. Severe adverse effects have been noted with pharmaceutical formulations containing diethylene glycol monoethyl-ethers and this led to withdrawal from the French market. The toxicity of GE depends on the molecular weight and the metabolites generated. It can manifest following acute or chronic exposure by disorders of the nervous system, bone marrow, immune system, kidneys as well as fertility, reproduction and embryofetal development. Several EGE are mutagenic. The carcinogenic risk is not known. The most toxic derivatives EGME, EGMEA, EGEE and EGEEA alter male and female fertility, and induce malformations. Taking these toxic effects into consideration, what is the place of GE as absorption promoting agents? An example is DEGEE, which facilitates estradiol penetration when used as a gel in the treatment of estrogen deficiency. This review is intended to address this issue.  相似文献   
1000.
OBJECTIVE: To review the diagnosis and treatment of postoperative femoral motor neuropathy without neurologic consultation or testing. STUDY DESIGN: A retrospective review of 6 consecutive patients with postoperative femoral motor neuropathy following gynecologic surgery. Diagnosis was made on clinical evaluation: history of falling during postoperative ambulation, quadriceps weakness, straight leg raise weakness, diminished knee jerk response, and no evidence of psoas hematoma or abscess. Neurologic consultation, electromyography, nerve conduction study and radiologic imaging, such as computed tomography, were not obtained. Instead, a physical therapy consultation was obtained for a knee orthotic and rehabilitation. RESULTS: Four postoperative femoral motor neuropathies developed following 3,014 cases of major gynecologic surgery (0.1%). Two additional cases were seen in consultation. The median age was 57 years. All patients fell while attempting ambulation on postoperative day 1. Recovery occurred at a median of 3 months (1-4). At a median follow-up of 4 years, no patient had developed additional neurologic sequelae. A history of prior postoperative femoral motor neuropathy was noted in 2 of 6 patients (33%). CONCLUSION: This was the first study of diagnosis and treatment of postoperative femoral motor neuropathy following gynecologic surgery without neurologic consultation or testing. Because of the significant expense of neurologic consultation and testing, patients with postoperative femoral motor neuropathy can have the condition diagnosed by the gynecologist and be referred directly to physical therapy without adversely affecting outcome. This also was the first study to elicit a prior history offemoral neuropathy in 33% of patients. Thus, a prior history may be a risk factor for recurrence.  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