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1.
An indirect enzyme-linked immunosorbent assay (ELISA) for the detection of hexoestrol (HES) was developed, optimized and validated for the analysis of HES in pork. Many parameters, such as the volume ratio of solution A and solution B, colour developing time, pH value, incubation time, the volume ratio of the standard solution and diluted antiserum, blocking solution, blocking condition, coating solution and coating condition were studied and optimized in the paper. The regression equation of the final inhibition curve is y = - 0.3345x + 1.4955, R2=0.9913. The linear range is 0.1-8.1 ng/ml, and the IC50 is 0.671 ng/ml. The specificity of the assay was evaluated by the cross-reactivity rates of six compounds, of which two structurally related compounds had a relatively higher cross-reactivity rate of 25% and 6%. HES was added into a pork sample at 5 ng/g level and then the sample was extracted. The recovery is between 49.6% and 79.2%, and the variation coefficient is 0.164.  相似文献   
2.
Fast T(1) mapping techniques are a valuable means of quantitatively assessing the distribution and dynamics of intravenously or orally applied paramagnetic contrast agents (CAs) by noninvasive imaging. In this study a fast T(1) mapping technique based on the variable flip angle (VFA) approach was optimized for accurate T(1) quantification in abdominal contrast-enhanced (CE) MRI. Optimization methods were developed to maximize the signal-to-noise ratio (SNR) and ensure effective RF and gradient spoiling, as well as a steady state, for a defined T(1) range of 100-800 ms and a limited acquisition time. We corrected B(1) field inhomogeneities by performing an additional measurement using an optimized fast B(1) mapping technique. High-precision in vitro and abdominal in vivo T(1) maps were successfully generated at a voxel size of 2.8 x 2.8 x 15 mm(3) and a temporal resolution of 2.3 s per T(1) map on 1.5T and 3T MRI systems. The application of the proposed fast T(1) mapping technique in abdominal CE-MRI enables noninvasive quantification of abdominal tissue perfusion and vascular permeability, and offers the possibility of quantitatively assessing dilution, distribution, and mixing processes of labeled solutions or drugs in the gastrointestinal tract.  相似文献   
3.
基于物料平衡理论建立了SMB色谱分离过程的理想数学模型。以提高产品纯度和叫率为目标,依据Massimo三角形理论,研究了主要操作参数对SMB性能的影响。针对具体的分离象进行了仿真和操作条件寻优,并以此指导实际分离实验,得到满意的结果。说明了简化的模型在操作优化、参数设计和分离预测中的作用。  相似文献   
4.
以功效系数为目标函数,相应地确定了设计变量和约束函数,对塑料注塑机合模机构的参数进行优化计算,提高了机构的综合性能。  相似文献   
5.
A number of pulse sequence techniques, including magnetization-prepared gradient echo (MP-GRE), segmented GRE, and hybrid RARE, employ a relatively large number of variable pulse sequence parameters and acquire the image data during a transient signal evolution. These sequences have recently been proposed and/or used for clinical applications in the brain, spine, liver, and coronary arteries. Thus, the need for a method of deriving optimal pulse sequence parameter values for this class of sequences now exists. Due to the complexity of these sequences, conventional optimization approaches, such as applying differential calculus to signal difference equations, are inadequate. We have developed a general framework for adapting the simulated annealing algorithm to pulse sequence parameter value optimization, and applied this framework to the specific case of optimizing the white matter-gray matter signal difference for a T1-weighted variable flip angle 3D MP-RAGE sequence. Using our algorithm, the values of 35 sequence parameters, including the magnetization-preparation RF pulse flip angle and delay time, 32 flip angles in the variable flip angle gradient-echo acquisition sequence, and the magnetization recovery time, were derived. Optimized 3D MP-RAGE achieved up to a 130% increase in white matter-gray matter signal difference compared with optimized 3D RF-spoiled FLASH with the same total acquisition time. The simulated annealing approach was effective at deriving optimal parameter values for a specific 3D MP-RAGE imaging objective, and may be useful for other imaging objectives and sequences in this general class.  相似文献   
6.
L-阿拉伯糖异构酶能将D-半乳糖异构成D-塔格糖。通过单因素试验和快速登高法对乳酸菌SK1.002产L-阿拉伯糖异构酶的培养基进行优化,确定发酵优化条件为(组分g/L):麦芽糊精28,酵母膏10,玉米粉浆22,无水乙酸钠10,K3PO40.2,NaCl 0.01,FeSO4.7H2O 0.01,Mg-SO4.7H2O 0.2,MnSO4.2H2O 0.05,L-阿拉伯糖2.5。发酵初始pH 8.4,培养温度37℃,接种体积分数3%,培养时间12 h。在此发酵条件下,酶活达到了7.28 U/mL。  相似文献   
7.
Eigenstructure assignment using output feedback is reformulated using an auxiliary principle of minimization of control effort. In the general eigenstructure assignment procedure, the feedback gain matrix is uniquely determined for a set of explicitly specified desired eigenvalues and eigenvectors. However, for the controller design proposed in this paper, only the most necessary constraints are imposed on the desired eigenvalues and eigenvectors, and the unspecified model parameters of the closed-loop system are determined by minimizing the control effort. Numerical examples are presented for comparison of the proposed method with standard eigenstructure assignment methods, and an experimental example gives an insight into the feasibility of the proposed control algorithm with application to the vibration control of flexible structures undergoing forced vibration.  相似文献   
8.
提出三个多项式凸轮曲线族。使用者可根据不同的用途,用优化方法求得待定系数值,从满足边界条件的曲线族中挑选出一条综合性能最优的凸轮曲线。还提供了待定系数与所选凸轮曲线的诸特性值之间关系的图表。  相似文献   
9.
An RF excitation pulse for three-dimensional (3D) time-of-flight (TOP) MR angiography (MRA) with a nonlinear excitation profile was numerically calculated under the condition of uniform vessel signal across the excitation volume (slab), and the superiority of the optform pulse as compared with conventional RF pulses and TONE pulses was demonstrated. For this purpose we acquired MRA of the lower leg and of the carotid and vertebral arteries in a 30-year-old healthy volunteer. Although the flow velocity ranges in these two anatomic locations are different by about a factor of 10, in both cases the corresponding optform pulse provided the best signal homogeneity at the highest level.  相似文献   
10.
Model building on the basis of Dutch cervical cancer screening data   总被引:1,自引:0,他引:1  
A mass screening programme for cervical cancer is in progress in three pilot regions in The Netherlands. All women living in these regions aged 35-53 are invited to undergo screening at three-year intervals. The MISCAN simulation model was developed for the analysis and optimization of screening programmes. In this paper the model-based approach to evaluation is first outlined and then illustrated by analysing data from the first two screening rounds in the pilot regions. This analysis resulted in a rather restricted range of data-compatible assumptions for the mean duration of preclinical disease (14-19 yr) and the frequency of spontaneous regression of preinvasive lesions (45-65%), as well as a rather wide sensitivity range for the Pap smear (50-90%). These preliminary findings are compared with those of a previous MISCAN analysis of cervical cancer screening in British Columbia. On the basis of an assumed 18-yr duration, 50% regression and 70% sensitivity, a number of screening policies relating to the same age ranges but with different intervals are compared. Both the analysis and the policy comparisons are preliminary, but the findings are nevertheless reasonable and consistent with those of previous studies. A more complete MISCAN-based analysis of the Dutch screening programme and subsequent optimization of screening policies will be possible when further results become available and a cost-effectiveness analysis procedure has been incorporated into the MISCAN programme.  相似文献   
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